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Talk:Communication Theory

About

 * Started: 23 October 2005
 * Size: 51,000 words (Sep 2008)

Purpose of this text
It has become something of a tradition that in communication theory seminars students provide some form of a "brief" of major theories, or an intellectual biography for a significant theorist. The Internet complicated this a bit, since many people now post these in one form or another. The approach taken here was to capture the results of a small seminar at the University at Buffalo, and make the work available to others. The hope is that this small set of chapters will encourage others to post their own versions.

Since a book is hardly a book (particularly when it comes to text books) unless there is some unified approach or schema, the assignment asked participants to pick out a theorist and use this person as an entry point into a range of theories. We would ask that those who contribute to the book read over the existing chapters and get a feel for the approach in order to provide a generalized feel throughout.

Theoretical perspective
I'm wondering if this is going to be a humanities approach to communications, or an engineering approach to communications? Are you talking about the ways people communicate and the effect it has, or are you talking on the specifics of communication schemes? --Whiteknight T C E 13:50, 27 October 2005 (UTC)

 * We are coming from the perspective of the social sciences and humanities. There is considerable ambiguity in the terms used, but I think there is something of a threshing out of this, with "communication theory" in the engineering sense often being enveloped by "Information Theory." That's the way it has (eventually) been sorted out over on Wikipedia. Halavais 15:23, 8 November 2005 (UTC)

A Good Beginning
Not a bad start. Make sure that Marcuse is added to the Frankfurt school. Also, a section on modernity and communication, featuring Habermas, Harvey, et al. will bring facilitate a more complete understanding of communication situated within a historical context. A section of conservative critique would also be benificial, featuring J.S. Mill and others on the implications of the mediocre mass that arises from a liberal-democratic model of communication. Sarkisian 30 January 2006 (UTC)

Naming convention
This book does not follow Naming policy. I suggest renaming pages using slash convention. --Derbeth 22:24, 6 November 2005 (UTC)

 * Thanks! Fixed (I think) Halavais 15:23, 8 November 2005 (UTC)

Structure
This is a great start, but I'm a bit shaky on the organizational structure. Perhaps one of us can systematically categorize the communication theories by the traditional contexts of semiotic, phenomenological, cybernetic, sociopsychological, sociocultural, and critical. I think your current approach is effective, and should remain intact; however, a supplementary chart that shows where these theories fall within the larger spectrum would also be of great help. I recommend the helpful charts in the back of Theories of Human Communication by Littlejohn and Foss, 8th edition, as a starting point. If I can get around to it, I will post a sample on this discussion page of what I mean. -- --bersumm

title: Talk:Communication Theory


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C++ Programming/Classes/Polymorphism

Dynamic polymorphism (Overrides)
So far, we have learned that we can add new data and functions to a class through inheritance. But what about if we want our derived class to inherit a method from the base class, but to have a different implementation for it? That is when we are talking about polymorphism, a fundamental concept in OOP programming.

As seen previously in the Programming Paradigms Section, Polymorphism is subdivided in two concepts static polymorphism and dynamic polymorphism. This section concentrates on dynamic polymorphism, which applies in C++ when a derived class overrides a function declared in a base class.

We implement this concept redefining the method in the derived class. However, we need to have some considerations when we do this, so now we must introduce the concepts of dynamic binding, static binding and virtual methods.

Suppose that we have two classes,  and. derives from  and redefines the implementation of a method   that resides in class. Now suppose that we have an object  of class. How should the instruction  be interpreted?

If  is declared in the stack (not declared as a pointer or a reference) the compiler applies static binding, this means it interprets (at compile time) that we refer to the implementation of   that resides in.

However, if we declare  as a pointer or a reference of class , the compiler could not know which method to call at compile time, because   can be of type   or. If this is resolved at run time, the method that resides in  will be called. This is called dynamic binding. If this is resolved at compile time, the method that resides in  will be called. This is again, static binding.

Virtual member functions
The virtual member functions is relatively simple, but often misunderstood. The concept is an essential part of designing a class hierarchy in regards to sub-classing classes as it determines the behavior of overridden methods in certain contexts.

Virtual member functions are class member functions, that can be overridden in any class derived from the one where they were declared. The member function body is then replaced with a new set of implementation in the derived class.

By placing the keyword virtual before a method declaration we are indicating that when the compiler has to decide between applying static binding or dynamic binding it will apply dynamic binding. Otherwise, static binding will be applied.

Again, this should be clearer with an example:

Our first calls to f and g on the two objects are straightforward. However things get interesting with our baz pointer which is a pointer to the Foo type.

f is not virtual and as such a call to f will always invoke the implementation associated with the pointer type—in this case the implementation from Foo.

Virtual function calls are computationally more expensive than regular function calls. Virtual functions use pointer indirection, invocation and will require a few extra instructions than normal member functions. They also require that the constructor of any class/structure containing virtual functions to initialize a table of pointers to its virtual member functions.

All this characteristics will signify a trade-off between performance and design. One should avoid preemptively declaring functions virtual without an existing structural need. Keep in mind that virtual functions that are only resolved at run-time cannot be inlined.

Pure virtual member function
There is one additional interesting possibility. Sometimes we don't want to provide an implementation of our function at all, but want to require people sub-classing our class to provide an implementation on their own. This is the case for pure virtuals.

To indicate a pure virtual function instead of an implementation we simply add an "<tt>= 0</tt>" after the function declaration.

Again—an example:

Because <tt>paint</tt> is a pure <tt>virtual</tt> function in the Widget <tt>class</tt> we are required to provide an implementation in all concrete subclasses. If we don't the compiler will give us an error at build time.

This is helpful for providing interfaces—things that we expect from all of the objects based on a certain hierarchy, but when we want to ignore the implementation details.

Let's take our example from above where we had a pure <tt>virtual</tt> for painting. There are a lot of cases where we want to be able to do things with widgets without worrying about what kind of widget it is. Painting is an easy example.
 * So why is this useful?

Imagine that we have something in our application that repaints widgets when they become active. It would just work with pointers to widgets—i.e. <tt>Widget *activeWidget const</tt> might be a possible function signature. So we might do something like:

We want to actually call the appropriate paint member function for the "real" widget type—not <tt>Widget::paint</tt> (which is a "pure" <tt>virtual</tt> and will cause the program to crash if called using virtual dispatch). By using a <tt>virtual</tt> function we insure that the member function implementation for our subclass -- <tt>Button::paint</tt> in this case—will be called.

Covariant return types
Covariant return types is the ability for a virtual function in a derived class to return a pointer or reference to an instance of itself if the version of the method in the base class does so. e.g.

This allows casting to be avoided.

virtual Constructors
There is a hierarchy of classes with base class <tt>Foo</tt>. Given an object <tt>bar</tt> belonging in the hierarchy, it is desired to be able to do the following:
 * 1) Create an object <tt>baz</tt> of the same class as <tt>bar</tt> (say, class <tt>Bar</tt>) initialized using the default constructor of the class. The syntax normally used is:
 * <tt>Bar* baz = bar.create;</tt>
 * 1) Create an object <tt>baz</tt> of the same class as <tt>bar</tt> which is a copy of <tt>bar</tt>. The syntax normally used is:
 * <tt>Bar* baz = bar.clone;</tt>

In the class <tt>Foo</tt>, the methods <tt>Foo::create</tt> and <tt>Foo::clone</tt> are declared as follows:

If <tt>Foo</tt> is to be used as an abstract class, the functions may be made pure virtual:

In order to support the creation of a default-initialized object, and the creation of a copy object, each class <tt>Bar</tt> in the hierarchy must have public default and copy constructors. The virtual constructors of <tt>Bar</tt> are defined as follows:

The above code uses covariant return types. If your compiler doesn't support <tt>Bar* Bar::create</tt>, use <tt>Foo* Bar::create</tt> instead, and similarly for <tt>clone</tt>.

While using these virtual constructors, you must manually deallocate the object created by calling <tt>delete baz;</tt>. This hassle could be avoided if a smart pointer (e.g. <tt>std::unique_ptr<Foo></tt>) is used in the return type instead of the plain old <tt>Foo*</tt>.

Remember that whether or not <tt>Foo</tt> uses dynamically allocated memory, you must define the destructor <tt>virtual ~Foo </tt> and make it <tt>virtual</tt> to take care of deallocation of objects using pointers to an ancestral type.

virtual Destructor
It is of special importance to remember to define a virtual destructor even if empty in any base class, since failing to do so will create problems with the default compiler generated destructor that will not be virtual.

A virtual destructor is not overridden when redefined in a derived class, the definitions to each destructor are cumulative and they start from the last derivate class toward the first base class.

Pure virtual Destructor
Every abstract class should contain the declaration of a pure virtual destructor.

Pure virtual destructors are a special case of pure virtual functions (meant to be overridden in a derived class). They must always be defined and that definition should always be empty.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: C++ Programming/Classes/Polymorphism


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Category:Basic foodstuffs

Basic ingredients upon which cooking is based.

title: Category:Basic foodstuffs


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Mac OS X Tiger/Appendix D

=Introduction= This Appendix contains the top 30 questions people ask when using Mac hardware and software. It's a good idea to read through this section before you use your Mac, as it will clarify some of the things you are likely to need answers to at first.

=The Questions=

I don't like the Apple mouse. How can I use my own mouse with my Mac?
If you'd prefer to use a non-Apple mouse, as many Mac users do, Apple is happy to accommodate you. Simply plug your mouse into your Mac and it will be automatically recognized, multiple buttons, scroll wheel, and all. You can use a PS/2 mouse with a PS/2 to USB adapter. Some mice require special software to work properly.

How do I right-click?
You can perform the equivalent of right-clicking in OS X by either holding down the mouse button, or by pressing Ctrl and clicking at the same time. If you have a Mighty Mouse (the mouse that ships with all modern Macs) you can also configure this for right clicking. Have a look in "Keyboard & Mouse" under System Preferences. Also, if you have a laptop Mac, you can do a right-click by clicking the touchpad with two fingers while properly configured.

How does my CD/DVD Drive Work?
Apple often uses slot loading optical drives that aren't commonly used by other computer makers. The way of interacting with the drives is also different from most others. If your drive looks like a thin slot, insert a disc and push it into the computer. The drive will catch onto the disc and read it. To eject the disc, press and hold the Eject key in the upper right-hand corner of your keyboard for a second.

If your drive is of the tray variety, press and hold your Eject key, or F12 on some keyboards, to open and close it. There is also an eject button next to the tray drives on some Macs, but this only works when a disc is already in the drive. If you are using a non-Apple or old Apple keyboard, you don't have an eject key. Right-click the disc's icon and choose "Eject" instead.

A Program has crashed and won't quit! What do I do?
Forcing an application to quit is called "Force Quitting" it. To do this, press ⌘⌥⎋ (Apple/Command-Option-Escape), choose the name of the crashed application from the list, and click the pulsating blue "Force Quit" button.

How do I empty the Trash?
The simplest way is to choose "Empty Trash" from the Finder menu (shortcut: ⇧⌘⌫). The Finder must be the frontmost application for this menu to appear in the menu bar. You can also press and hold the trash icon, and a menu will appear with an "Empty Trash" option.

Why can't I cut files using Finder?
If you were a Windows user you may wonder why OS X doesn't allow you to "cut" files and then paste them somewhere else in Finder. Apple has chosen to disable this feature for various reasons. The easiest alternative is to move the file(s) by dragging and dropping using the "spring-loaded folders" feature.

Where can I get support?
There are many resources available where you may seek help. First, basic questions may be answered in your Mac's, or an application's help files. New computers come with 90 days of telephone support and one year of limited parts coverage. AppleCare extends that coverage to 3 years of telephone support and parts coverage. There are also numerous communities that will assist you with your Mac (usually in the form of forums), including Apple's very own "Discussions" area of the support section on their site. More resources can be found on Apple's support site, or third party documentation, which can usually be found through search engines. You may also receive free support at any one of Apple's Genius bars (with appointment). Some technicians may also be able to assist you, at a price.

How do I select multiple items on some web forms?
Under Windows, you may be used to holding down the "shift" or "control" keys to select multiple items. In Mac OS X, use the Command key instead of Control to select items that aren't next to each other. Holding Shift allows you to select a number of items that are all together. The Control key is normally used to display a contextual menu when using a single-button mouse. If you have a two button mouse, you can right-click to achieve the same thing.

Where can I find a program for...
Finding software for Macs can be hard at times since it's not used as much as Windows in many contexts. Fortunately there are sites like versiontracker.com and macupdate.com which have databases of the newest versions of most OS X software. Another good resource is MacintoshSoftware.net. If you can't find the software you need there, ask on a forum.

title: Mac OS X Tiger/Appendix D


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User talk:66.245.112.198

i see you've been making alot of good edits. If you hit the "Show Preview" button on the bottom of the edit box, you can see what you've written so far, so you dont need to keep making edits, and going back in to change things. Also, if you register for a user name, you can get credit for all your edits. --Whiteknight T C E 02:20, 25 October 2005 (UTC)

Thanks for your advice. This is the first time for me to use this Wiki Editor. May I know how to add pictures? (png file) ? Do you write PLC ( Programmable Logic Control) for this web site ? Thanks.

title: User talk:66.245.112.198


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User:TwoThirty

My ability at communication in the English language is better than my ability in Arabic, at the present, though. I go under the same user name in Wikipeda. I am working on the "Learn Arabic" wikibook in the English wikibook site.

title: User:TwoThirty


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User:Joe Petrick

Wrote the chapter on The Frankfurt School

title: User:Joe Petrick


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User:Strongbad/North American Football/The Football Field

The football field may differ slightly from place to place, but all football fields have some things in common. One of the first things one notices about a football field is that it has a 100-yard middle capped off by 10-yard end zones. These end zones are distinguished by markings on the field. Also, the field is surrounded by a giant white line. At the side of the field, this line forms the sideline of the field. There are fine white markings down the middle of the field. These are hash marks, which the ball is always placed between before it is snapped, and the spacing depends on what type of football is being played. The thick white lines running the width of the field are yard lines, which aid in the determination of the ball's position. Above each end zone is a crossbar.


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User:Wolfrider~enwikibooks

 * Meta-Wiki User Page

title: User:Wolfrider~enwikibooks


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User:Strongbad/North American Football/Offense

The offense is the bread and butter of a team's scoring, so naturally, it is the most exciting part of the game. The offensive unit consists of five offensive linemen and six "skilled" players. One of the skilled players is usually the quarterback, who initiates offensive plays and is the offense's focal point. The other skilled players may be running backs, who are either halfbacks or fullbacks, wide receivers, and tight ends. Each player's job in a play depends on what kind of play it is, but mainly, it depends on whether it is a running or a passing play.

The offensive lineman's job is simple, and it leads to their sheer size on the field. A lineman's size should not be underappreciated because being squashed by one of these guys can be quite painful and is not good for your health in the long term. They are required to keep defensive linemen and linebackers away from the running back and quarterback. They do this by simple blocking, but some linemen will "pancake" a defender, which means that the defender is pushed to the ground. If a defender is pancaked, the defense is essentially short by one man. A lineman does not want a defensive player to push past him, but this happens on almost every play.

No discussion of the offense is complete without mentioning the quarterback's duties. He calls for the ball to be snapped from the center to initiate the play. On a running play, the quarterback does not do much other than hand the ball off. On a passing play, however, the quarterback gets to shine. He must throw the ball to an open receiver before the defense gets to him. The position of quarterback is arguably the most demanding position in football.

The position of running back requires a good deal of bravery. One of the running back's jobs is obvious from the name; he runs with the ball, hoping to gain good yardage and possibly a touchdown. Another job is blocking, and the fullback, who is generally bigger than the halfback, does this often. A halfback on a team with a strong passing game can expect to block a lot, though. The running backs can also catch passes. This can create mismatches for the defense.

The wide receiver is the main passing threat on offense. He is normally one of the smallest and fastest men on the field. They are required to catch passes from the quarterback (and, occasionally, the halfback). When a team looks for big yardage, the wide receiver is normally who it turns to. The wide receivers don't play a big role in running plays; they generally lead cornerbacks and safeties upfield so the running back can cover more ground.

Although every skilled position seems to call for multiple offensive talents, the tight end has the most split job after the quarterback. On some plays, they act just like offensive linemen and block defenders. On other plays, particularly near the opponent's goal line, they can catch passes. This makes them dangerous on the field.


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Adventist Youth Honors Answer Book/Vocational/Carpentry

Band Saw
A band saw is a saw that can be used for woodworking, metal working, and a variety of other materials. It gets its name from its blade, consisting of a narrow band of toothed metal. This band rides on two large wheels stacked vertically with a space between them. Band saws are particularly useful for cutting irregular shapes. The radius of a curve that can be cut on a particular saw is determined by the width of the band.

Belt Sander
A belt sander is a machine used to quickly sand down wood and other materials for finishing purposes. It consists of a motor that turns a pair of drums on which a seamless loop of sandpaper is mounted. Belt sanders can be either hand-held, where the sander is moved over the material, or stationary (fixed), where the material is moved to the sanding belt. Stationary belt sanders are often combined with a disc sander.

Belt sanders can have a very aggressive action on wood and are normally used only for the beginning stages of the sanding process, or used to rapidly remove material.

Jig Saw
A jigsaw (also called saber saw or saber saw) is a type of saw used for cutting arbitrary curves, such as stenciled designs or other custom shapes, into a piece of wood or similar material. It is usually used in a more artistic fashion than other saws, which only cut in straight lines and exist mainly to chop pieces of wood to length for building structure. The first jigsaw puzzles were made using this kind of saw.

Traditional jigsaws are hand saws, consisting of a handle attached to a small, thin blade. More modern jigsaws are power tools, made up of a motor and a reciprocating saw blade.

Miter Saw
Today, a miter saw (also called a chop saw or drop saw) usually refers to a power tool used to make a quick, accurate crosscut in a workpiece. It is most frequently used to cut wood, although some plastics and light metals can also be cut with the tool. Common uses include framing operations and the cutting molding. Most miter saws are relatively small and portable, with common blade sizes ranging from eight to 12 inches.

The miter saw makes cuts by pulling a spinning circular saw blade down onto a workpiece in a short, controlled motion. The workpiece is typically held against a fence, which provides a precise cutting angle between the blade and the longest workpiece edge. In standard position, this angle is fixed at 90°.

Radial Arm Saw
A radial arm saw is a machine intended for cutting materials to length. It is primarily a woodworking machine, although it is sometimes used for cutting metals, such as angle iron or aluminum extrusions. Before the advent of the radial arm saw, table saws and hand saws were most commonly used for crosscutting lumber. Table saws are ideal for ripping stock, but it is awkward to push a long piece of stock widthwise through a table saw blade. When a radial arm saw is used, the stock remains stationary on the saw's table and the blade is pulled through the stock.

Router
A router is a woodworking tool used to route out (hollow out) an area in the face of a piece of wood. It was a tool particularly used by pattern makers and consisted of a broad-based wooden hand plane with a narrow blade projecting well beyond its base plate. Since about 1960, it has been replaced by the modern spindle router, which was designed for the same work. Further refinement has produced the even more recent plunging spindle router, which is even better adapted for many types of work.

Shaper
A wood shaper is a stationary woodworking machine in which a spindle spins at moderately high speeds. Specially shaped bits are mounted on the spindle. As the workpiece is fed into the machine, the bit cuts a profile into it. On some shapers, router bits can also be used using a special mounting adapter.

Wood shapers do essentially the same job as the router table, with the main difference being that a wood shaper is a stationary machine designed for larger volume work while a router table is a hand tool for lighter duty work. Routers can also be mounted on a router table, and used as a stationary tool. However, routers run at considerably higher speeds than shapers, and the use of large bits can be dangerous. Also, shapers can be used to cut much larger profiles than routers and custom-made shaper bits can be readily ordered or fabricated.

Block Plane
A block plane is designed to cut end grain and is typically small enough to be used with one hand. To use it, securely clamp the piece to be planed to a solid object (ideally, a work bench). Then pass the plane's sole across the endgrain you are trying to smooth. The blade can be adjusted, and it is best to set it such that the blade barely protrudes out of the bottom of the plane. Adjust it so that it takes very thin shavings. If no wood is removed, let the blade out a little more.

Circular Saw (cut a straight line)
Note: Participants must be at least 16 years old to use power tools It is vitally important that you describe the dangers involved in using a circular saw before you turn your Pathfinders loose on one. It is very easy to cut off a finger or cause an even more serious injury with one of these. If your Pathfinders are a little scared (not petrified) of this tool, that's a good thing. One should never get too comfortable with dangerous equipment.

Make sure the lumber is well supported before attempting to cut it, and make sure that you closely supervise the use of this tool. The operator should also wear eye protection.

Adjust the blade so that the depth of cut just exceeds the thickness of the board you wish to cut. You can run the blade right over the top of a saw horse this way. This will cut a small groove in the sawhorse, but that's an acceptable use of the tool.

If cutting plywood, you can clamp a piece of lumber along the line so that the shoe of the saw can rest against it and use it as a guide. Make sure the saw can clear the clamps on both ends of the cut though. Also make sure that the operator doesn't have to overreach to complete the cut and that all hands, feet, limbs, small children, and pets are clear of the area.

Framing Square
A framing square is used to make sure that an angle is 90°. Place the corner of the square next to the angle you wish to check, and adjust the angle until it lines up with the square. To check that the square itself is square, mark a straight line and place one edge of the square along this line. Then mark another line along the other edge of the square, intersecting the first line near the center of its length. Finally flip the square and see if the other side of the first line and the second line form also a 90° angle.

Hammer
Grip the hammer near the end of the handle opposite the hammer's head. Many people grip the handle near the hammer's head, but this is incorrect. When driving a nail, the hammer must be maneuvered so that its flat face strikes the nail's head at a right angle to the nail's axis, with the head moving parallel to that axis. Failure to achieve either condition will result in a sideways force on the nail's head, that may bend it. Also, one should relax the muscles of the hand and arm momentarily when the hammer strikes.

Hand Saw (cut a straight line)
Handsaws are tools used for cutting wood. Handsaws come in many varieties, including the crosscut saw, rip saw, coping saw, tenon saw, backsaw, and dovetail saw. Each has its own special use. A crosscut saw is used for cutting across the grain of a piece of lumber. A rip saw is used for cutting along the grain. A coping saw is used for making curved cuts. A tenon saw is used for cutting tenons and other fine work. A backsaw is commonly used with a miter box and for small cutting jobs. A dovetail saw is used for cutting dovetail joints.

To use a crosscut or a rip saw, place the board on a supported surface at thigh-height (between the knee and hips). Grip the saw with the right hand (assuming right-handedness) and use the left knee to hold the board in place. Align the right shoulder, arm, and hand so that they are in line with the cut to be made. Begin with light strokes, noting that the saw cuts on the push stroke. As the cut progresses, keep an eye on the line, pulling the blade toward it. If this is to be a "finished" cut, you can score a "V" along the line first with a carton knife, and let the blade ride in the V groove. Score another line along the bottom of the board to prevent tear-out.

Maintain your saws by keeping them dry and sharp. Many tools (including saws) can be kept in great condition by wiping them down with a cloth and oil (or WD40) after each use.

Level
A level is a tool designed to indicate whether a surface is level or plumb. A level surface has no tilt to it, so that liquid would pool up on the surface rather than run off. A plumb surface is straight up and down. Ideally, you want your floors to be level and your walls to be plumb.

Most levels have two bubbles on them - one for checking levelness, and the other for checking plumbness. To use the level, lay its edge on the surface you wish the check. Embedded in the middle of the level is a small window where the bubble and the tube is mounted. Two rings designate where the bubble would be if the surface were level (or plumb). If the bubble is not centered between these two rings, the surface is not level. Lift one edge of the level off the surface to see how far you have to move it in order to move the bubble between the lines. This will give you an indicator of how much correction is required to make the surface level. Adjust and remeasure, repeating until the surface is level.

Measuring Tape
A measuring tape is more commonly known as a "tape measure." It is used for measuring the length of an item. There is a metal tape curled into a spiral inside the enclosure, and attached to a spring. When the tape is pulled out of the enclosure, the spiral unwinds and the spring is tensed. When the tape is released, the spring draws it back into the enclosure. A hook on the end of the tape prevents it from being completely drawn inside, and this hook can also be used for hooking the end of the tape to the edge of a board. The tape itself is marked with inches, and these can be read off to measure a board or to mark a line for a cut. Between each inch mark are smaller tick marks. The largest of these is halfway between each inch marking, and indicates the half-inch measure. Slightly smaller tick marks lie between the half-inch mark and the inch marks, and these mark off the quarter-inch increments. Between each of the quarter inch marks are smaller marks to indicate eighths. Some tapes also mark off sixteenths (sometimes only for the first several inches). See the illustration to see how to read the markings.

Most tape measures also show 1 foot increments (often with a black square) as well as showing 16-inch increments (often with a red square). The 16-inch increments are useful because studs, joists, and rafters are commonly 16 inches apart.

Nail Set
A nail set is used in finish carpentry to drive a nail below the surface of a board. First the nail is driven with a hammer until it is very near the surface of the board. Then the tip of the nail set is placed on the nail head. Finish nails have a small divot in the head to accept the nail set. The head of the nail set is then struck with the hammer until the nail is driven below (or flush with) the surface of the board.

Plumb Bob
A plumb bob is a weight on the end of a string. The weight will hang straight down and is used as a reference for a perfectly vertical line. It can be used in some places where a level cannot - such as in a place where there is no vertical surface to place the level against. For example, a carpenter may wish to find a place on the floor just below a point on a ceiling joist so he can construct an interior non-weight bearing wall there and then be able to tie it into the ceiling joist. In this case, the wall does not yet exist, so there is nothing to place a level against to measure for plumbness.

Wood Chisel
Wood chisels are most commonly used in carpentry for installing recessed hinges. To do this, the hinge is laid on the board to which it will be attached, and then it is traced. The hinge is then removed, and a sharp knife is used to score around the hinge's outline. A chisel is then used to remove wood to a depth equal to the hinge's thickness.

3. Describe the use of and distinguish between the following types of nails: 20 Penny, 16 Penny, 12 Penny, 8 Penny, 6 Penny, Finish, Brad, Roofing, Screw Nail, Sinker, Common, and Galvenized

 * Penny: The penny size is written with a number and the abbreviation d for penny (e.g. - 10d). D is an abbreviation for denarius, a Roman coin similar to a penny; this was the abbreviation for a penny in the UK before decimaliation. A smaller number indicates a shorter nail and a larger number indicates a longer nail. Nails under 1-1/4 in., often called brads, are sold mostly in small packages with only a length designation (e.g. 1/2" (12 mm), 1-1/8" (28 mm), etc.).

 * Finish nail: A finish nail is used for interior woodworking. Size varies, but the head of the nail is only slightly larger than the nail's shaft.  A finish nail is set by driving its head below the surface of the wood using a nail set.  The head can then be covered with putty (for a natural finish) or with caulk (for a painted finish).  If done well, this makes the nail effectively invisible.

 * Brad: Brad nails are small and often made of brass. They are often used to hold small pieces of trim in place.  Rather than attempting to hide the nail, brads sometimes have decorative heads, so that the nail head becomes part of the decor.

 * Roofing nail: A roofing nail is short with a large, flat head. It is also coated with zinc to prevent rusting.  Roofing nails are used for attaching shingles to a roof.

 * Screw nail: A screw nail has a twisted shank for extra holding power.

 * Sinker: A Sinker nail's head is tapered on the underside, so that the nail can be driven flush with the surface of the board. These are used in general construction.

 * Common: A Common nail has a flat head and is used for general construction, carpentry, and framing.

 * Galvanized: A Galvanized nail is a nail that has been coated with zinc to inhibit corrosion. Galvanized nails are often used in work that will be exposed to weather.

== 4. Assist in erecting a building not less than 6x8 feet in ground dimensions with a gable roof and at least one door and one window, demonstrating ability to measure and use tools from requirement 2. == This requirement is just begging you to build a shed, though other options are certainly possible as well. Many Pathfinders go on mission trips to help build churches or schools, and if your group is planning to do this, you have the perfect opportunity to earn this honor.

In the United States (and in most developed countries) the local government will require a building permit for a shed, even one as small as this. Check with the local government and review the building codes before starting this project. They will usually want a drawing showing what you plan to build before issuing a permit.

If building a small shed, you may be able to use a "floating" foundation - that is special concrete blocks in the shape of a trapezoid (wider at the base than on top). The blocks sit on the ground, and beams are placed in notches on top of these. The floor joists and headers (which join to the end of the joists) are built on top of the beams. Once the floor is built, the walls can be framed (including openings for the doors and windows). At this point, the walls can be sheathed and the roof can be framed, sheathed, and shingled as well. Then the doors and windows are installed, the siding is put on, and the finish carpentry begins on the inside (though this step can be skipped on a shed).

Be sure that your Pathfinders each use all the tools called out in requirement 2. It might be a good idea to make a checklist for each Pathfinder, and have them compare their activities to it as the day progresses to be sure they use all the tools required.

Floor Joist
A floor joist is a board that supports the floor. Depending on how large an area the floor covers, and how far the joists span, the floor joist can be anywhere from a 2x6 to a 2x12, or even bigger. Floor joists are installed edgewise, and they are attached to headers which attach to the foundation of the building.

Sub Floor
The sub floor is usually made from plywood, particle board, or oriented strand board (OSB), and is nailed (or screwed) to the floor joists. The finished floor (carpeting, hardwood floor, laminate floor, linoleum, vinyl, tile, etc.) is then laid atop the sub floor.

Shoe Plate
More commonly known as a bottom plate or a sole plate, a shoe plate is the bottom board in a framed wall. Studs are nailed into this board, and it is nailed to the floor. Some local building codes require that the shoe plate be made of pressure treated lumber to resist rot if water pools on the floor (for whatever reason).

Top Plate
The top plate is the board running along the top of a framed wall. Like the shoe plate, the studs are nailed to this board, and it is attached to the ceiling.

Double Plate
For added strength, two top plates are used, most commonly on a weight-bearing wall. The upper top plate is called the cap plate.

Conventional Roof or Trusses
A conventional roof is made from rafters which are beams that run from the roof's ridge to the ceiling joists. A truss is an engineered, pre-built structure consisting of triangles. Trusses are lighter, stronger, and cheaper than rafters, but they form a web of lumber inside the roof rendering the attic space unusable. Rafters are positioned in line with the studs in a wall and are fastened to both the top plate and the ceiling joists. A pair of rafters (joined to the opposite sides of the ridge board) are sometimes tied together with a collar beam which is a horizontal member.

Felt Roof
Felt roofing material is not like the felt sets used in the children's Sabbath School classes. Rather, "felt roofing" is just another name for tar paper. Before installing the felt roofing, you should first nail a drip strip to the edges of the roof. Then the felt paper is rolled out over the entire horizontal length of the roof (not top to bottom!) and stapled onto the sheathing. If the felt is not wide enough to cover the roof from the eaves to the peak, you will need another layer. The first layer should be along the eaves, and subsequent layers should overlap previous ones by a couple of inches. If the roof has a ridge vent, do not cover it. The purpose if a ridge vent is to allow heat to escape from the attic. Covering it with tar paper defeats this feature completely. The roof is now ready to shingle.

Shingles
Shingles are laid on top of the felt roofing, starting with the bottom row. Use roofing nails to attach asphalt shingles directly to the felt roofing. The next row of shingles should be offset from the first so that the boundary between two shingles and the notches that make up the tabs in one shingle are completely covered by the tab of another - not by another boundary or by a notch. The shingles should overlap such that only the tabs show, and not the solid portion on the upper part of the shingle. It helps tremendously to mark parallel lines on the tar paper with a chalk line so that the shingles do not creep uphill. You want the line to be level.

Window with Weight-bearing Header
A window opening must have a weight-bearing header. The header is a pair of 2x4's which are turned on their edges and nailed to a stud. A pair of studs (called jack studs) run from the bottom of the header to the floor to help support the weight. Short studs (called cripple studs then run from the header to the top plate. The cripple studs supply a support for the wall's sheeting.

Door with Weight-bearing Header
As with windows, doors also require a weight-bearing header. It is built exactly the same way a window opening is made.

Fascia on Eaves
Fascia is a "finish" board that covers the ends of the rafters.

Siding
The purpose of siding is to keep water out of the building. Vinyl siding is, in general, easier to work with than aluminum siding, but there are other options too, including asphalt, weather boards, and plain old plywood with felt paper beneath and with furring strips covering the joints. It's always good to consult with different websites, when you need to install new siding in order to find out how much of it you will need for your project.

Note
Participants must be 16 years old or older to use power tools.


text:
Wikibooks talk:Reading room/Bulletin Board

The latest bulletin is a year old. Perhaps this page should be discontinued? At least it should not be linked from the main wikibooks page Juliusross 04:52, 25 October 2005 (UTC)

 * There are a number of "current news" items that could potentially go up here, but for somebody willing to volunteer to keep this page up to date. Indeed, Wikibooks has been in the news quite a bit lately from a number of different places.  In particular, the French newspaper Liberation just did a major article on Wikijunior and Wikibooks.... surprisingly talking quite a bit about the English Wikibooks in addition to the French port of the project.  The numbers are a little off because they claim a total of 12,000 titles, when in fact that is the module count.  Title count on Wikibooks is in the range of a few hundred, but it is still impressive when you think about it.

 * Ideally, this should be updated. For now, this is historical information about the origins of Wikibooks and some early press coverage.  I don't see a reason to delete this page, but perhaps a disclaimer that this is heavily out of date and that we need a volunteer to add updated news regarding Wikibooks.  The 10,000th Wikibook module went by with little fanfare except for a brief mention at meta and the Staff Lounge.  As far as linking from the main page is concerned, I don't see too much problem with that but perhaps it could be moved to the Community Portal page instead?  That is another page which is in dire need of updating as well.  --Rob Horning 07:03, 25 October 2005 (UTC)

 * Are there any good places within the community to get some news (e.g. the 10,000 module). Like is the Mailing list a good place?
 * Also is this page not better named as "News" then? I thought it would be a kind of forum Juliusross 13:28, 25 October 2005 (UTC)
 * I personally wouldn't object to this page being renamed "news" instead of Bulletin Board. Wikipedia has a "news" section, and Quarto is the overall Wikimedia "news" publication (and of course there is Wikinews for general news as well).  We just havn't been too organized in this regard.  Surprisingly, Google News is perhaps the best bet right now to find out what people outside of this project are saying about us.  The mailing list is a joke and mainly a bunch of early contributors to Wikibooks.  It is, however, a good way to get quick communication to the Wikimedia Foundation board regarding Wikibooks activities.  Staff Lounge is a much better forum for general communications within Wikibooks, but even that doesn't always get monitored.  Better than most places, however.  If you are willing to "volunteer" and turn this into a general news area about current happenings with Wikibooks, I would like to encourage you to do that.  Some exciting things are happening with Wikibooks, and it would be nice to be able to point out major accomplishments when they occur.  I just don't have the time to do all the organization I know it will take to rework this page.  --Rob Horning 16:28, 25 October 2005 (UTC)

 * Without promising too much I will try and make the page a little more current, and perhaps even rename it when I figure how to. I have high hopes for wikibooks and do not like seeing it look like it is dormant.  Juliusross 23:41, 25 October 2005 (UTC)

 * Thanks for the effort so far. You are correct, we need to keep pages like this fresh.  One of the problems with Wikibooks is that most contributors here tend to hunker down and work on their little pet Wikibook, which takes quite a bit of time to flesh out.  In contrast, Wikipedia can typically get a major article completed quickly, not only because those articles are shorter but there are usually more contributors willing to help.  After adding a half dozen articles, many people are willing to branch out and work on "website infrastructure" like links between pages and content organization.  The process of doing that here on Wikibooks, like just about everything else, tends to take quite a bit longer to happen.  --Rob Horning 15:21, 26 October 2005 (UTC)

Dead?
Does any one watch this page? I posted some practical news here and don't even know if anyone reads them...

Tip for everyone: you can post here everything that has project-wide meaning: request for adminship, new CSS class, change in important template etc. --Derbeth talk 07:39, 2 December 2005 (UTC)

 * I'm watching this page... mainly for vandalism. Still, it would be nice to add a little bit more "news".  I don't have the time to keep this current, but it would be nice to make some project-wide happenings put here as a brief note of what is going on.  It looks like more is happening off the Staff Lounge page more and more, so this might become a useful place to keep a quick eye on what is happening on Wikibooks before you discover that decisions have been made without you.  The community portal page needs similar work.  --Rob Horning 21:27, 2 December 2005 (UTC)

 * We've been trying hard to resurrect this page, and hopefully people will be adding more news to it as time goes on. --Whiteknight (talk) (projects) 19:01, 12 December 2006 (UTC)

 * How does this page differ from other pages like the Staff Room, Admins' Noticeboard, etc.? I'm watching this page also but I don't know why.  Xania [[Image:Flag_of_Poland_2.svg|15px]]talk 08:58, 9 January 2007 (UTC)

 * Staff Lounge is an active discussion forum. Bulletin board is more of a 1-line or 2-line summary of an important event. I didn't know this page existed for a while, but now I watch it. --Dragontamer 15:41, 9 January 2007 (UTC)

 * Xania probably doesnt need to watch it, because he's already involved in all the discussions. The bulletin board is just a place to share news to users, and if you already know all the news, you don't need to watch it. --Whiteknight (talk) (projects) 20:15, 9 January 2007 (UTC)

 * I was going to ask 'but how do people find this page?' but then I noticed that it's linked from the sidebar. Maybe it should be called 'Wikibooks News' or something that calls out for people to read it.  'Bulletin board' just suggests it's some kind of forum and so won't be visited by many users. Xania [[Image:Flag_of_Poland_2.svg|15px]]talk 20:25, 9 January 2007 (UTC)

 * Perhaps we should rename the link to be "Bulletin board|Wikibooks News", or something like that, but I dont think we should rename this page entirely. --Whiteknight (talk) (projects) 20:45, 9 January 2007 (UTC)

RSS feed
It'd be really nice to have an RSS feed for this. We could easily have a RC bot check for additions to the project page and upload data to be added to an existing rss and atom file. I could create the php backend, except that I know little about protecting the files from hijackers, so probably not. I doubt the rcbot would be too difficult to create. Who has an always-on server (at their home, I assume) they're willing to host it on? Since it would only be text, anyone one of the major editors getting a free hosting service would probably be sufficient. Cheers, Iamunknown 18:46, 12 December 2006 (UTC)

 * I don't currently an always-on server, but I have been planning to create one sometime soon. I have a server machine (PII, Redhat linux, Apache), but it isn't connected. What I need to do is boot up my server, update all the old software, register a domain name, and set up some bot software to run on it. But you are right, some kind of feed for the bulletin board would be nice. --Whiteknight (talk) (projects) 19:01, 12 December 2006 (UTC)

 * Mediawiki has an RSS feed for every page. Go to "history" and it appears in toolbox. The one for this (talk) page is here... lol. The one for this page itself is here --Dragontamer 22:58, 8 January 2007 (UTC)

 * Regardless, I dont think this page changes nearly enough to warrant a different RSS feed. It would be a very boring feed indeed. --Whiteknight (talk) (projects) 00:54, 9 January 2007 (UTC)

Creation of a math formulas page
I think that it would be a great asset for anyone in the math field if there was a site where a majority of the formulas could be found. This was suggested by the people at wikipedia. from: trd89 @ wikipedia March 2, 2007
 * Isn't that already the function of Table of integrals, Table of derivatives, et. al.? --Iamunknown 06:16, 3 March 2007 (UTC)

 * The Calculus book contains a few pages with such lists, and there is another similar work at Engineering Tables, which serves as a shared "appendix" for a number of other books on the engineering bookshelf. --Whiteknight (talk) (projects) 23:10, 4 March 2007 (UTC)

Needed?
The old discussion is being reincarnated. Is this page really necessary? Yes, I visit it and it's on my watch list but is it really necessary? There are so many pages for general discussion - assistance, Bulletin Board, Technical, General discussion, Project discussion, etc. Given that this is a small wiki do we need so many?--ЗAНИA talk 00:56, 5 November 2009 (UTC)

Also given what I've just said, was it wise for me to even bother posting my comment here?--ЗAНИA talk 00:56, 5 November 2009 (UTC)

 * It's on my WL too, but I don't think anyone ever comes here (well... how would I know?) It's certainly not serving its intended purpose, and as you note, other pages seem to be filling that role just fine. --Jomegat (talk) 01:55, 5 November 2009 (UTC)

 * News postings ought to have a place on the main page, if anywhere, for visibility, but there's not enough involvement to discuss redesigning it. We're still doing better than Wikiversity:News, but there's not enough activity to justify this page.  If not deleted entirely, I suggest that this page and User:WikimediaNotifier/notifications be removed from Reading room/Navigation and this page be removed from the navigation at left, to put the focus on pages that more of the community is actively watching, if not actively involved in.  This page in particular is the first link in the navigation under the community heading and creates the terrible impression that this wiki is dead.

 * For that matter, Wikibooks in the media linked from the unimpressive Community Portal hasn't been updated since 2007 either. Let's clean up the cobwebs and get rid of these. -- Adrignola talk contribs 14:52, 17 November 2009 (UTC)

 * This isn't intended to be a discussion page, rather news about Wikibooks that Wikibookians consider to be of importance so that people who have been gone awhile have a place to turn to learn what importance things have happened. This includes things like when a proposal becomes a policy, if new extensions become enabled, etc. --dark lama  16:20, 24 November 2009 (UTC)

 * I'm putting the indexes on the reading room root instead. This page can go back to being stagnant. -- Adrignola talk contribs 16:29, 24 November 2009 (UTC)

starting a new book
ok, how do i do it?Ldecola (discuss • contribs) 22:50, 23 November 2011 (UTC)

 * See if something already exists and if not start a new page in the Wikibooks main namespace. For instance MyBook (you can also use your userspace for drafting your concept first and then move the page).  --Panic (discuss • contribs) 23:26, 23 November 2011 (UTC)
 * Chazz has also replied to the question of your talk page and I have posted the welcome information that may be relevant for you. --Panic (discuss • contribs) 23:29, 23 November 2011 (UTC)

RfC notice
Thanks to Uncle G for informing people about the Internet Defense League RfC. Just a quick remark that it is not true that "Unfortunately, the Foundation representatives only directly notified that part of the community that is on the English Wikipedia" - this was posted on Wikimedia-l (formerly Foundation-l), quite the usual venue for such issues, and on the "Wikimedia Forum" on Meta. (Also, I am wondering whether an unsigned announcement is the right place for opinionated personal remarks of that kind.) Regards, Tbayer (WMF) (discuss • contribs) 15:19, 29 June 2012 (UTC)


text:
Category:Lasagne recipes

Recipes for Lasagne.

title: Category:Lasagne recipes


text:
Category:Appetizer recipes

Recipes for Appetizers.

es:Categoría:Aperitivo hy:Կատեգորիա:Խորտիկներ

title: Category:Appetizer recipes


text:
Category:Beverage recipes

Recipes for beverages.

de:Kategorie:Kochbuch/ Getränke es:Categoría:Bebidas hy:Կատեգորիա:Խմիչքներ nl:Categorie:Drank

title: Category:Beverage recipes


text:
US Internet Law/Communications Decency Act

Two provisions of the Communications Decency Act of 1996 (CDA or Act) sought to protect minors from harmful material on the Internet. 47 U.S.C. §223(a)(1)(B)(ii) criminalized the "knowing" transmission of "obscene or indecent" messages to any recipient under 18 years of age. Section 223(d) prohibits the "knowin[g]" sending or displaying to a person under 18 of any message "that, in context, depicts or describes, in terms patently offensive as measured by contemporary community standards, sexual or excretory activities or organs."

Affirmative defenses are provided for those who take "good faith, . . . effective . . . actions" to restrict access by minors to the prohibited communications, §223(e)(5)(A), and those who restrict such access by requiring certain designated forms of age proof, such as a verified credit card or an adult identification number, §223(e)(5)(B). A number of plaintiffs filed suit challenging the constitutionality of §§223(a)(1) and 223(d).

In ACLU v. Reno, after making extensive findings of fact, a three-judge District Court convened pursuant to the Act entered a preliminary injunction against enforcement of both challenged provisions. The court's judgment enjoined the Government from enforcing §223(a)(1)(B)'s prohibitions insofar as they relate to "indecent" communications, but expressly preserves the Government's right to investigate and prosecute the obscenity or child pornography activities prohibited therein. The injunction against enforcement of §223(d) was unqualified because that section contains no separate reference to obscenity or child pornography. The Government appealed to the Supreme Court under the Act's special review provisions, arguing that the District Court erred in holding that the CDA violated both the First Amendment because it is over-broad and the Fifth Amendment because it is vague. The Supreme Court held that the CDA's "indecent transmission" and "patently offensive display" provisions violated the First Amendment.


text:
Category:Dessert recipes

Recipes for dessert.

de:Kategorie:Kochbuch/ Desserts es:Categoría:Postre hy:Կատեգորիա:Աղանդերներ nl:Categorie:Dessert

title: Category:Dessert recipes


text:
User talk:72.56.44.27

If you want to post your opinion, please use talk pages. --Derbeth 09:20, 25 October 2005 (UTC)

title: User talk:72.56.44.27


text: User talk:165.228.131.11

title: User talk:165.228.131.11


text:
User talk:65.116.143.82

Please stop. If you continue to blank pages, you will be blocked from editing.

title: User talk:65.116.143.82


text: User talk:68.71.11.144

title: User talk:68.71.11.144


text: User talk:212.138.64.178

title: User talk:212.138.64.178


text:
User talk:82.34.28.193

Please stop adding nonsense to Wikibooks. It is considered vandalism. If you would like to experiment, use the sandbox. Thank you.

title: User talk:82.34.28.193


text: User talk:81.164.165.76

title: User talk:81.164.165.76


text:
User talk:81.108.165.190

Please stop adding nonsense to Wikibooks. It is considered vandalism. If you would like to experiment, use the sandbox. Thank you.

title: User talk:81.108.165.190


text:
A-level Physics/Electrons, Waves and Photons/D.C. circuits

A direct current (DC) circuit usually has a steady and constant voltage supplied to it. A direct current does not have a continually changing polarity, unlike an alternating current (AC), but instead a constant direction and rate of flow. DC is generally provided by batteries or via a transformer, rather than generators.

Circuit diagrams
Below are the symbols and names for all of the components that you are required to know:

Series circuits
When resistors are set up in series, the formula to work out the total resistance is:

$$R_T = r_1+r_2+r_n...etc$$

Where $$r_1, r_2$$ etc., are the resistance of each resistor in series.

Parallel circuits
When resistors are set up in parallel, the formula to work out the total resistance is:

$$\frac{1}{r_t}=\frac{1}{r_1}+\frac{1}{r_2}+\frac{1}{r_n} ...etc$$

Where $$r_1, r_2$$ etc., are the resistance of each resistor in parallel.

Internal resistance
A electrical source has its own resistance, known as Internal Resistance. This is caused by the electrons in the source having to flow through wires within it, or in the case of a chemical battery, the charge may have to flow through the electrolytes and electrodes that make up the cell.

By considering a battery of EMF E, in series with a resistor of resistance R we can calculate the internal resistance r:

$$E=I(R+r)$$     (See Series Circuits above)

Combining with V=IR:

$$V=E-Ir$$

The quantity Ir is called the lost volts. The lost volts shows us the energy transferred to the internal resistance of the source, so if you short circuit a battery, I is very high and the battery gets warm.

Potential dividers
A potential (or voltage) divider is made up of two resistors. The output voltage from a potential divider will be a proportion of the input voltage and is determined by the resistor values.

The values of a battery with voltage V1 passing through two resistors in series of resistance R1 and R2, with an output circuit in parallel with Resistor R1 with output voltage V2 are related by the equation: $$V1=(R1/(R1+R2))$$ × $$V2$$

Kirchhoff's laws
First Law states "The sum of the current (A) entering a junction is equal to the sum of the current (A) leaving the junction". This is a consequence of conservation of charge.

Second law states that the EMF is equal to the voltage of the circuit. This is a consequence of conservation of energy.

Use of other components
Thermistors can be placed in circuits when temperature plays a role. As the temperature increases, the resistance of the device decreases. This does not obey the Ohms law. Light dependent resistors are resistors that decrease their resistance when exposed to light.


text:
User talk:Oki~enwikibooks

So long as you are logged in, you have 2 options to upload a picture:
 * 1) on the lower right-hand side of your screen, you can click the link "Upload File", and upload your image.
 * 2) You may also upload images on the Commons, although i dont know exactly how.

Once you've uploaded an image, you can put it in your artical like this:

For more information on "how-to" stuff, check out The Image help page. You can also leave me a message on my talk page, and I'll help you out the best I can. --Whiteknight T C E 14:02, 25 October 2005 (UTC)

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Oki. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Oki~enwikibooks that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

Yours, Keegan Peterzell Community Liaison, Wikimedia Foundation 23:34, 17 March 2015 (UTC)

Renamed
 This account has been renamed as part of single-user login finalisation. If you own this account you can |log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: . -- Keegan (WMF) (talk) 05:19, 19 April 2015 (UTC)

title: User talk:Oki~enwikibooks


text:
Communication Systems

Introduction
This book will eventually cover a large number of topics in the field of electrical communications. The reader will also require a knowledge of Time and Frequency Domain representations, which is covered in-depth in the Signals and Systems book. This book will, by necessity, touch on a number of different areas of study, and as such is more than just a text for aspiring Electrical Engineers. This book will discuss topics of analog communication schemes, computer programming, network architectures, information infrastructures, communications circuit analysis, and many other topics.

''This book is still in an early stage of development. Many topics do not yet have pages, and many of the current pages are stubs. Any help would be greatly appreciated.''

Table of Contents

 * /Communications Introduction/
 * /Communications History/

System Examples
This section will provide a brief overview of the more common communications systems in use today. The demarcation between these systems is quite artificial since a wireless VoIP Internet connection may be a combination of all of these individual systems.

 * /Telephone System/
 * /Cellular Systems/
 * /Packet Data Systems/
 * /Satellite Systems/
 * /Microwave Systems/
 * /Fiber Optic Systems/

Communications Basics
This section will examine some theory common to many communication systems. Examples are, what constitutes a signal, information, channels, multiplexing etc.

 * /Baseband and Broadband Signals/
 * /Time-Division Multiplexing/
 * /Frequency-Division Multiplexing/
 * /Voltage-Controlled Oscillators/ (VCO)
 * /Envelope Filters/ (Envelope Detectors)
 * /What is Modulation?/
 * /Analog vs. Digital/
 * /Communication Mediums/
 * /Coherent Receivers/

Analog Modulation
This section will examine the nature and conveyance of continuously varying information signals.

 * /Analog Modulation Introduction/
 * /Amplitude Modulation/ (AM)
 * /Frequency Modulation/ (FM)
 * /Phase Modulation/ (PM)
 * /FM and PM Generalization/
 * /AM Receivers/

Digital Modulation
This section considers the nature and encoding of discrete information signals.

 * /Pulse Amplitude Modulation/ (PAM)
 * /Binary Modulation Schemes/
 * /M-ary Modulation Schemes/
 * /Quadrature Amplitude Modulation/ (QAM)
 * /Noncoherent Receivers/
 * /Line Codes/

Transmission
This section examines various communications media and its characteristics. Any communication system may contain one or more of these media types.

 * /Wave Propagation/
 * /Antennas/
 * /Noise Figure/
 * /Wired Transmission/
 * /Wireless Transmission/
 * /Space-Division Multiplexing/
 * /Fading Channels/

Appendices

 * IEEE 802 Working Groups

Resources and Licensing

 * /Resources/
 * /Licensing/

title: Communication Systems


text:
Control Systems

Special Pages

 * Preface

Controls Introduction

 * Introduction
 * System Identification
 * Digital and Analog
 * System Metrics
 * System Modeling

Classical Control Methods

 * Transforms
 * Transfer Functions
 * Poles and Zeros

Modern Control Methods

 * State-Space Equations
 * Linear System Solutions
 * Time-Variant System Solutions
 * Digital State-Space
 * Eigenvalues and Eigenvectors
 * Standard Forms
 * MIMO Systems
 * Realizations

System Representation

 * Gain
 * Block Diagrams
 * Feedback Loops
 * Signal Flow Diagrams
 * Bode Plots
 * Nichols Charts

Stability

 * Stability
 * State-Space Stability
 * Discrete-Time Stability
 * Routh-Hurwitz Criterion
 * Jury's Test
 * Root Locus
 * Nyquist Stability Criterion

Controllers and Compensators

 * Controllability and Observability
 * System Specifications
 * State Feedback
 * Estimators and Observers
 * Eigenvalue Assignment for MIMO Systems
 * Controllers and Compensators
 * Polynomial Design

Adaptive Control

 * Adaptive Control

Nonlinear Systems

 * State Machines
 * Nonlinear Systems
 * Common Nonlinearities

Noisy Systems

 * Noise Driven Systems

Introduction to Digital Controls

 * Digital Control Systems
 * Discrete-Time Stability
 * System Delays
 * Sampled Data Systems
 * Z Transform Mappings

Linear Matrix Inequalities in Control

 * Linear Matrix Inequalities
 * A List of Linear Matrix Inequalities in Control

Examples

 * Examples

Appendices

 * Physical Models
 * Transforms
 * System Representations
 * Matrix Operations
 * Using MATLAB ®
 * Using Octave
 * Using Julia
 * Using Scilab
 * Using Python

Resources, Glossary, and License

 * Glossary
 * List of Equations
 * Resources
 * Licensing

תורת הבקרה 制御システム

title: Control Systems


text:
Digital Signal Processing

With the explosion of digital communications and digital media, the need for methods to process digital data is more important than ever. This book will begin with a look at the mathematical concepts behind digital processing, then will build on that with particular algorithms to do the work, and finally will present the actual implementations of these techniques in today's hardware and software systems. Many real-world algorithms are based on the techniques described in this book. JPEG images, MP3 songs, MPEG-2 videos, and ZIP files are all processed using digital processing techniques, and all of them will be discussed, at least conceptually. This book will not teach programming, and will probably not even provide much in the way of actual code, so we don't need to worry much about computer language dependence, except where otherwise noted. For some solid background information on the various mathematical theories in this book, consider reading Signals and Systems.

''This book is in a very early stage of production, and many of the pages either don't exist or only exist as bare stubs. Help and contributions from all wikibookians will be very much appreciated!''

Table of Contents

 * /Introduction/
 * Software tools

Digital Signals

 * /Discrete Data/
 * /Discrete Operations/
 * /Digital Systems/
 * /Impulse Response/
 * /Sampling and Reconstruction/

Transforms

 * /Continuous-Time Fourier Transform/ (CTFT)
 * /Discrete-Time Fourier Transform/ (DTFT)
 * /Discrete Fourier Transform/ (DFT)
 * Fourier Series Expansion (FSE)
 * /Z Transform/
 * /Hilbert Transform/
 * /Fast Fourier Transform (FFT) Algorithm/

Digital Filters

 * /Digital Filters/
 * /FIR Filter Design/
 * /IIR Filter Design/
 * /Filter Representation/
 * /Tunable Filters/
 * /Infinite Input Filtering/
 * /Computer-aided Filter Design/
 * /Ideal Filters/
 * /Least Squares Design/

Analog Filter Modeling

 * /Analog Filter Design/
 * /Spectral Transforms/
 * /Analog Mappings/
 * /Bilinear Transform/

Digital Processing

 * /Discrete Cosine Transform/
 * /Haar Transform/
 * /Quantization/
 * /Multirate DSP/
 * /Windowing/

Filter Implementation

 * Filter Verification
 * Implementability

Modulation

 * Phase Modulation
 * /Sigma-Delta modulation/

Noise and Errors
channel of noises
 * Finite wordlength effects
 * Clipping
 * Quantization Effects
 * Roundoff errors
 * Limit Cycles
 * Discrete Stochastic Process

Multirate Systems

 * Upsampling and Downsampling
 * /Multirate Filters/
 * Decimation and Interpolation
 * Polyphase decomposition

Advanced Filters

 * Dynamic Range Scaling
 * Filter Sensitivity

Spectral Analysis

 * Classical
 * nonparametric
 * Parametric
 * Linear Prediction

Adaptive filters

 * /Wiener Filters/
 * Normal Equations
 * Kalman Filtering

Applications

 * /DSP Programming/
 * /Sound Processing/
 * /Image Processing/
 * /Digital Signal Processors/

Appendices

 * /Transforms/

Resources and Licensing

 * /Resources/
 * /Licensing/

Digitale Signalverarbeitung

title: Digital Signal Processing


text:
Embedded Systems

Preface
This book is about microcontrollers, in the field of digital control systems. We will discuss embedded systems, real-time operating systems, and other topics of interest. It is important to realize that embedded systems rarely have display capabilities, and if they do have displays, they are usually limited to small text-only LCD displays. The challenge of programming an embedded system then is that it is difficult to get real-time feedback from the system without a display. It is common to use a simple serial interface for diagnostic purposes, for example by connecting to a PC running terminal software via a RS-232 to USB adapter. Also, embedded systems usually have very strict memory limitations, processor limitations, and speed limitations that must play a factor in designing an embedded system, and programming an embedded computer. This book talks about some of the specific issues involved in programming an embedded computer. It also covers some basic topics such as microprocessor architectures, FPGAs, and some general low-level computing topics. While many of the issues discussed in this book may apply to PCs, and non-embedded computers, this book remains focused on topics that apply to embedded systems only.

This book has incorporated a number of smaller books, stub-books, and half-books that were previously written about this subject.

Table of Contents

 * Embedded Systems Introduction
 * Terminology

Microprocessor Basics

 * Microprocessor Introduction
 * Theory, Design and Implementation
 * Embedded System Basics
 * Microprocessor Architectures
 * Programmable Controllers
 * /Floating Point Unit/ and fixed-point numbers
 * Parity
 * Memory
 * Memory Units
 * /Watchdog Timer/

Programming Embedded Systems

 * /C Programming/
 * /Assembly Language/
 * /Mixed C and Assembly Programming/
 * I/O Programming
 * Serial and Parallel I/O
 * /Super Loop Architecture/
 * /Protected Mode and Real Mode/ (x86)
 * /Bootloaders and Bootsectors/
 * /Terminate and Stay Resident/ (TSR)

Real Time Operating System

 * Real-Time Operating Systems (RTOS)
 * Threading and Synchronization
 * Interrupts
 * RTOS Implementation
 * Locks and Critical Sections
 * Common RTOS

 * Palm OS
 * Windows CE
 * MS-DOS or DOS Clones
 * Linux

Interfacing

 * /Interfacing Basics/
 * External ICs
 * /Low-Voltage Circuits/
 * High-Voltage Circuits

Particular Microprocessor Families

 * Particular Microprocessors
 * Intel Microprocessors
 * PIC Microcontroller
 * PIC programming
 * 8051 Microcontroller
 * Freescale Microcontrollers
 * /Texas Instruments MSP430 microcontrollers/
 * Atmel AVR
 * Operating systems and task managers
 * /ARM Microprocessors/
 * /ARM Assembly Language/
 * /ARM Instructions/
 * AT91SAM7S64
 * Cypress PSoC Microcontroller
 * Cypress PSoC application notes

Appendices

 * Common Protocols
 * Where To Buy

Resources and Licensing

 * /Resources/
 * /Licensing/

Sulautetut järjestelmät 嵌入式系统

title: Embedded Systems


text:
Georgia Water/Georgia Water Council

Overview
The Georgia Water Council, as sequel to the Georgia Water Resources Council, was created by the Comprehensive State-wide Water Management Planning Act, from HB237, signed by Governor Sonny Perdue on May 13, 2004. This Act is based on the work of the Joint Comprehensive Water Plan Study Committee of 2001-2002. It replaced the River Basin Management Planning Act of 1992.

Duties
Duties of the Georgia Water Council as specified in the Act (OCGA 12-5-524(b)) include:
 * 1) Ensure coordination, cooperation, and communication among state agencies and their water related efforts in the development of a comprehensive state-wide water management plan;
 * 2) Provide input to the Georgia EPD concerning the development of a comprehensive state-wide water management plan;
 * 3) Review, modify if necessary, and approve the final draft of the proposed comprehensive state-wide water management plan; and
 * 4) Recommend such initial proposed plan for consideration by the General Assembly not later than ... the first day of the 2008 regular session of the General Assembly.

Members
The member composition of the Georgia Water Council is specified in the authorizing legislation, O.C.G.A. Section 12-5-524, Comprehensive State-wide Water Management Planning Act (SB 237 of 2004).

Members of the Georgia Water Council are listed on the Council's website, and shown below in the order written in O.C.G.A. 12-5-524(a).

A. Two Appointed Members (Both voting members)
 * One member is appointed by the Speaker of the House of Representatives, and one member is appointed by the President Pro Tempore of the Senate; each appointee shall not be a member of the General Assembly and shall serve for a term of four years and until a successor is appointed and qualified.
 * Gus H. Bell III of Savannah (|appointed appointed by Georgia Senate President Pro Tem Eric Johnson (R-Savannah))
 * Jerry Lane of Claxton Poultry (appointed by House Speaker Terry Coleman (D-Eastman))

B. Eight Directors of Georgia State Agencies (All 8 ex-officio)
 * Carol Couch, Georgia Environmental Protection Division (chair of Water Council)
 * Noel Holcomb, Georgia Department of Natural Resources
 * David Bennett, Georgia Soil and Water Conservation Commission
 * Mike Beatty, Georgia Department of Community Affairs
 * B.J. Walker, Georgia Department of Human Resources
 * Tommy Irvin, Georgia Department of Agriculture
 * Kenneth Stewart Jr., Georgia Forestry Commission
 * Paul Burks, Georgia Environmental Facilities Authority

C. Four Elected Representatives (2 ex-officio, 2 appointed, and all 4 advisory/non-voting)
 * The chairperson of the Senate Natural Resources and the Environment Committee, ex officio, and one additional member of that committee to be selected by its chairperson and the chairperson of the House Committee on Natural Resources and Environment, ex officio, and one additional member of that committee to be selected by its chairperson shall each serve in an advisory capacity (O.C.G.A. 12-5-524(a)).
 * Senator Ross Tolleson (R-Perry), Chair of Senate Natural Resources and Environment Committee
 * Senator John Bulloch (R-Ochlocknee), District 11
 * Representative Lynn Smith (R-Newnan), Chair of House Committee on Natural Resources and Environment
 * Representative Tom McCall (D-Elberton), District 30

Procedures
Administrative procedures:
 * quorum
 * voting
 * minutes
 * public participation

title: Georgia Water/Georgia Water Council


text:
User:Allefant~enwikibooks

Blender_3D:_Noob_to_Pro book

 * Wrote the panoramic rendering tutorial
 * Wrote most of the first python scripting tutorial

title: User:Allefant~enwikibooks


text: User:Nicombo

title: User:Nicombo


text:
User talk:Nach0king

Come introduce yourself at the new users page. If you have any questions, you can ask there or contact me personally. Kellen T 20:15, 25 October 2005 (UTC)
 * Please also check out the Cookbook policy page and the Cookbook talk pages.
 * You also need to use the "Cookbook:" prefix for any links that are supposed to be inside the cookbook, e.g. turnip

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Nach0king. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Nach0king~enwikibooks that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

Yours, Keegan Peterzell Community Liaison, Wikimedia Foundation 23:31, 17 March 2015 (UTC)

title: User talk:Nach0king


text:
User talk:134.39.27.36

You have been temporarily blocked from editing Wikibooks. You were warned several times that linking to commercial sites is not allowed. If you wish to make useful contributions, you are welcome to come back after the block expires.

title: User talk:134.39.27.36


text:
User talk:85.169.43.136

Please stop adding nonsense to Wikibooks. It is considered vandalism. If you would like to experiment, use the sandbox. Thank you.

title: User talk:85.169.43.136


text:
User:Xerol

Notices and other stuff
Somewhat active again, see Projects below for where I'll be working.

Useful Links
Mostly for my use, but also because some of these are hard to find:
 * Vandalism in progress
 * Deletion_policy

Contact Me
I'm also on the Wikibooks IRC channel most of the time.
 * AIM: XerolOplan
 * ICQ: 125672905
 * MSN: xeroloplan@hotmail.com
 * Yahoo: xerol3
 * My Wikipedia userpage. Even when I'm inactive I still read wikipedia so if you post on my talk page, I'll get the notice.

Projects

 * Template Sandbox

Diagrams and Illustrations
I'll be making nice vector diagrams whereever helpful, probably putting them up on commons.

My Cleanup Tasks
See User:Xerol/Cleanup.

SoftwareVersion templates and Manual of Style
Working on templates for use in the SoftwareVersions project.

Miscellaneous
Feel free to comment in each section; feedback is always appreciated, especially if I'm wrong.

title: User:Xerol


text:
User talk:Xerol

Semi-active, doing RC patrol, cleanup tasks, and working on software version guidelines for the Manual of Style

 * Archives: 2/06-4/09

Accountancy
I just spent a bit of time commenting on your proposed organization of the Introduction to Accounting (or just Accountancy) book, and then I noticed that you had done it almost four years ago. I'm just curious. Have you abandoned this project?

I'm also curious as to your background. A book on accounting? Another book on Cellular Automata? This sounds a lot like my background. (I double degreed while I was in college, with a B.S. in Computer Science and a B.B.A. in Accounting. I then went on in Accounting with a M.Acc., a CPA, CMA, and am currently in the Fiscal Services Department of a local government.)  But this is purely curiousity on my part. Feel free to ignore this question if you think it's too personal, or just delete it. --fcoulter (talk) 20:56, 2 August 2009 (UTC)

I acted on the merge and removed the Complex Analysis Handbook RfD
I acted on the merge request (not opposed) and removed your RfD. Since there is no need for archival or to establish a special closing of the RfD the only avenue was to remove the request itself. Feel free to edit the changes to Complex Analysis. --Panic (talk) 17:22, 11 July 2010 (UTC)
 * Unless the proponent of the RfD objects, I see no need to restore the RfD (though if there is an objection, it definitely gets restored). Panic — for future reference, cutting the Gordian knot by unilaterally removing someone else's RfD could go badly wrong if it were taken amiss, and there is (on reflection) an alternative that would fall safely within procedure, and get the job done: do the merge, and add a comment to the RfD saying you've done it.  The nominator has the opportunity to respond within the process, and if they agree, the RfD can simply be closed.  --Pi zero (talk) 18:28, 11 July 2010 (UTC)
 * Yes I considered using the comment option, but decided that if any brouhaha would happen it would be reduced to those implicated and not extend to the rest of the community since at least I'm confident that two of us will be able to rapidly resolve any issue I selected the option that could create less distraction to the rest of the community. If Xerol objects to my action of course I will agree that the removal of the RfD should be undone and we will discuss it further there. --Panic (talk) 18:43, 11 July 2010 (UTC)
 * In any case we should think about a solution to this cases, IIRC this is the second time I've aborted one RfD using the same method but as you state it can be a cause of conflict (depending on those involved) since most abortable RfD originate in users with less experience and because of that more probable to escalate the issue. The action is made safe under BeBold, putting the issue of removing signed posts. --Panic (talk) 18:53, 11 July 2010 (UTC)
 * Perform a non-admin closure and leave it up for a week. It can then be archived. – Adrignola talk 19:41, 11 July 2010 (UTC)

For the record the actual merge done borders on vandalism. It appears to be a blind copy and paste of material from one book into the other with disregard of the content written in the page and elsewhere in the book, style, notation, etc. Now the page on the derivative defines the derivative twice in the same module. Derives the Cauchy Riemann equations, in two consecutive modules and duplicates much of the material. And material from the introduction of the book now appears as if for the first time at the beginning of Chapter 2. I just don't understand why such the rushed job? Why not look over the new book a little first? I will take a little time and see what I can do about cleaning it up. But I really wish you hadn't done the merge in the first place, it would have been easier to get right the first time. Thenub314 (talk) 20:38, 11 July 2010 (UTC)
 * Calling vandalism is a bit too harsh Thenub314, nothing was destroyed and people can improve on what is there. I refrained of doing any reshuffling and complied with the non objected proposals for merge (the claim that I increased complexity is also unfounded), even Xerol clearly noted that some content was usable so I simply removed the need to put the process of salvage in the hands on the general community to the people that really are interested in working on it. Since Xerol RfD did spur interest in the content something constructive may result (I also did contact the Wikibooians working on the books and the original merge tagger). It was not a blind copy but also nothing more than a merge of related content. In any case it's best to discuss what to salvage that what to delete, it also may create a chance for you to add to it.
 * I think that it would be more constructive to do what you see as needed changes in place of making hash judgments. I'll gladly appreciate any help you can provide in improving it. --Panic (talk) 20:52, 11 July 2010 (UTC)
 * Basically I RfD'd it because I wanted to spur a bit of discussion, not being familiar with the topic, amongst those who could properly merge the material. I only noticed the page to begin with as part of my war on orphans, saw the merge notice, checked page histories, saw that a few constructive edits had been made since the merge notice was put up, looked at the merge target book, and then went to RfD to get comments. I even mentioned in the RfD that it seemed like the content could not be readily merged into the other book, simply because the writing styles were very different, and also mentioned that I only had limited knowledge on the topic, which I intended as a clue that someone more knowledgeable should take a look at it and inform the decision. Where did I "clearly note that some content was usable"? I said there wasn't much that could be merged that would add anything to the larger, more developed book. (Original edit here)
 * I know that no one really "owns" a book but in nearly every case of dealing with subject matter with which I was unfamiliar I've elected to notify those who seem to be the primary editors on a book that action should be taken. In this case, had I not decided to put it up for an RfD (for instance, if there had been a lot of meaningful material that didn't appear in the other book, but the stubbier book was clearly still incomplete and completely inactive) I would've at the very least replaced the mergefrom notice (which appears to never have been placed to begin with; the history merge makes it very confusing though), and at least left a note on the TOC's talk page plus any user talk pages as appropriate. If nothing had been done about it within a week or so I might've acted on my own (or, in this case, asked a friend with 2 master's degrees in math). Basically there's a lot of ways to do what was done, and the way this was handled seems like one of the worse ways to do it. But, looking through the pages with my limited knowledge, there was value added to the post-merge pages so it's not like a ridiculously egregious act was committed here. Lines may have been crossed but it all worked out in the end, so let's all learn some lessons and move on. Xerol Oplan (talk) 23:53, 11 July 2010 (UTC)

 * I take that we are all done on this subject. I have been talking with Thenub314 and I assure you if anyone can have any blame here is me for being unable to predict this storm in a teacup. Sorry about the use of your talkpage but since you were the proponent of the RfD it seems unavoidable. Since you demonstrated interest on that content now merged I inform you that of the 70 lines of text on the original 3 pages, soon after the merge, only ~10 lines remain.
 * In regard to the BeBold I urge you to take on your own words and proceed in updating the manual of stile. I'm having a "soft" dispute regarding necessary distinction we need to make on the C++ Programming book as a requirement to inform readers on the version that is covered (C++0x is almost out and some information is already being put on the book). It would be nice to point to an accepted the text even if not a guideline to establish common ground. --Panic (talk) 06:15, 13 July 2010 (UTC)
 * I need to clean up the text a bit (writing in an instructional/informative tone is something I have difficulty with) but I can put up an abridged version for now and add to it. There is a consensus that it should be added, so it'll get in there sooner or later, just probably a bit later as the MOS is something that I feel requires a little more carefulness than boldness. Xerol Oplan (talk) 06:20, 13 July 2010 (UTC)

Template
It would be useful also to cover "also covers" (if the information is mixed together) and "the next version" (even if it isn't a direct improvement it would be easier to search for the template after the release and fix it). Just some thoughts based on what would be required on the C++ Programming book (see C++0x), and due to some changes need to be covered next to existing "old version" content. --Panic (talk) 22:16, 13 July 2010 (UTC)
 * You can put any text you want as the SoftwareVersion parameter, for example you could say "0.47 and newer". DeprecationType probably isn't the best name for that parameter, but if you wanted a separate designation for "Unreleased" or "Future" it could be added. Xerol Oplan (talk) 22:40, 13 July 2010 (UTC)
 * Added "Newer" and "Future" versions. Xerol Oplan (talk) 22:40, 13 July 2010 (UTC)

title: User talk:Xerol


text:
SNFO Flight Planning/Situational Awareness Wind Triangle

If this were an ideal world in which to fly, there would be no wind. If the aircraft were set to fly a particular ground track, the aircraft would not be blown off course by wind. The aircraft's ground speed would also be equal to its true airspeed, but as we have seen, this is not usually the case. The one element that affects ground speed and track is the effects of wind.


text:
Guide to Unix/Explanations/bc

bc is an arbitrary-precision decimal calculator language. The arbitrary-precision means that numbers can contain an arbitrary number of digits before the decimal point, limited by memory; most other languages limit numbers to eight bytes at most. The number of digits after the decimal point is per default zero, but can be set to a fixed number called "scale".

"bc" is often called using the "-l" option. The option loads the standard library containing mostly trigonometric functions available as single letters, and sets the number of decimal places for division to 20.

Overview
Bc at a glance:

Example session
This is an example of a user starting bc, doing two calculations, and exiting with "quit". Note that pressing ^D (control-D) also exits.

$ bc -l 3 + 4 7 2 / 5 .40000000000000000000 quit $

binary numbers
Conversion from decimal ratio to binary

bc 1.06 Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc. This is free software with ABSOLUTELY NO WARRANTY. For details type `warranty'. obase=2 3/14 .0011011011011011011011011011011011011011011011011011011011011011010 1/5 .0011001100110011001100110011001100110011001100110011001100110011001

Example script
''Some versions of "bc" limit function and variable names to one letter. The following example has long function and variable names and must be changed to work on these copies of "bc".''

The following example was tested with OpenBSD bc and has also been verified with Gnu bc version 1.06 patchlevel 2.

This script implements Simpson's rule for integration. The function "integrate" approximates the definite integral from "a" to "b" using "n" parabola sections. The formula for "simpson" is taken from the Wikipedia article. This example integrates the sine function, but different functions can be used by replacing f.

define f(x) { return s(x); } define simpson(a,b) { return ( (b-a)/6 ) * ( f(a) + 4*f((a+b)/2) + f(b) ); } define integrate(a,b,n) { delta = (b - a) / n;  result = 0; for(i = a; (n = n - 1) + 1; i = i + delta) { /*print "calling simpson(", i, ", ", i + delta, ") with n = ", n, "\n";*/ result = result + simpson(i, i + delta); }  return result; }

Put this in a file, say "simpson", load it, and integrate f from 0 to pi (pi is "4*a(1)", 4 times arctangent of 1) with 100 intervals: $ bc -l simpson integrate(0, 4*a(1), 100) 2.00000000067647189101 ^D

Limitations

 * Bc does not support floating-point arithmetic. It supports fixed-point arithmetic, and the fixed number of decimal points can be set to be rather large, via scale.
 * bc does not allow numbers to be entered in the scientific notation, like 5.031E10.
 * No operators for bitwise manipulation (| for or, & for and, ^ for xor, <<, >>) in POSIX and GNU bc.
 * No operators for logical and and or (&&, ||) in POSIX bc; present in GNU bc as an extension.
 * Very limited number of functions in the standard library. Many additional functions are provided by Gavin Howard bc.

Standard library
Standard library is loaded when bc is called with the "-l" option. The library contains mostly trigonometric functions available as single letters. The library is usually implemented in bc itself and thus serves as examples of bc use. The functions included are s (sin), c (cos), a (atan), l (log), e (exp) and j (the bessel function).

Links:
 * libmath.b in bc-21, opensource.apple.com – actually GNU bc used in Linux as well
 * bc.library in freebsd-src, github.com
 * bc.library in openbsd/src, github.com
 * lib.bc in gavinhoward/bc, github.com
 * lib2.bc in gavinhoward/bc, github.com – extension functions

Decimal vs. binary
As specified by POSIX, bc shall behave as if performing the calculation using decimal representation in the digits after decimal point rather than the usual binary representation. One consequence is that 0.1 is exactly representable and that 0.1 * 3 is exactly 0.3, which is not the case in languages that use binary representation.

title: Guide to Unix/Explanations/bc