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LaTeX/Errors and Warnings

LaTeX describes what it is typesetting while it does it. If it encounters something it doesn't understand or can't do, it will display a message saying what is wrong. It may also display warnings for less serious conditions.

Don't panic if you see error messages: it is very common to mistype or misspell commands, forget curly braces, type a forward slash instead of a backslash, or use a special character by mistake. Errors are easily spotted and easily corrected in your editor, and you can then run LaTeX again to check you have fixed everything. Some of the most common errors are described in the next sections.

Error messages
The format of an error message is always the same. Error messages begin with an exclamation mark at the start of the line, and give a description of the error, followed by another line starting with the number, which refers to the line-number in your document file which LaTeX was processing when the error was spotted. Here's an example, showing that the user mistyped the \tableofcontents command:

! Undefined control sequence. l.6 \tableofcotnetns

When LaTeX finds an error like this, it displays the error message and pauses. You must type one of the following letters to continue:

Some systems (Emacs is one example) run LaTeX with a "nonstop" switch turned on, so it will always process through to the end of the file, regardless of errors, or until a limit is reached.

Warnings
Warnings don't begin with an exclamation mark: they are just comments by LaTeX about things you might want to look into, such as overlong or underrun lines (often caused by unusual hyphenations, for example), pages running short or long, and other typographical niceties (most of which you can ignore until later). Unlike other systems, which try to hide unevennesses in the text (usually unsuccessfully) by interfering with the letter spacing, LaTeX takes the view that the author or editor should be able to contribute. While it is certainly possible to set LaTeX's parameters so that the spacing is sufficiently sloppy that you will almost never get a warning about badly-fitting lines or pages, you will almost certainly just be delaying matters until you start to get complaints from your readers or publishers.

Examples
Only a few common error messages are given here: those most likely to be encountered by beginners. If you find another error message not shown here, and it's not clear what you should do, ask for help.

Most error messages are self-explanatory, but be aware that the place where LaTeX spots and reports an error may be later in the file than the place where it actually occurred. For example if you forget to close a curly brace which encloses, say, italics, LaTeX won't report this until something else occurs which can't happen until the curly brace is encountered (e.g. the end of the document!) Some errors can only be righted by humans who can read and understand what the document is supposed to mean or look like.

Newcomers should remember to check the list of special characters: a very large number of errors when you are learning LaTeX are due to accidentally typing a special character when you didn't mean to. This disappears after a few days as you get used to them.

Too many }'s
! Too many }'s. l.6 \date December 2004}

The reason LaTeX thinks there are too many }'s here is that the opening curly brace is missing after the \date control sequence and before the word December, so the closing curly brace is seen as one too many (which it is!). In fact, there are other things which can follow the \date command apart from a date in curly braces, so LaTeX cannot possibly guess that you've missed out the opening curly brace until it finds a closing one!

Undefined control sequence
! Undefined control sequence. l.6 \dtae {December 2004}

In this example, LaTeX is complaining that it has no such command ("control sequence") as \dtae. Obviously it's been mistyped, but only a human can detect that fact: all LaTeX knows is that \dtae is not a command it knows about: it's undefined. Mistypings are the most common source of errors. Some editors allow common commands and environments to be inserted using drop-down menus or icons, which may be used to avoid these errors.

Not in Mathematics Mode
! Missing $ inserted

A character that can only be used in the mathematics mode was inserted in normal text. If you intended to use mathematics mode, then use $...$  or \begin{math}...\end{math} or use the 'quick math mode': \ensuremath{...}. If you did not intend to use mathematics mode, then perhaps you are trying to use a special character that needs to be entered in a different way; for example <tt>_</tt> will be interpreted as a subscript operator in mathematics mode, and you need <tt>\_</tt> to get an underscore character.

Since 2018, all TeX engines support UTF-8 encoding. In older versions, this can also happen if you use the wrong character encoding, for example using UTF-8 without "\usepackage[utf8]{inputenc}" or using iso8859-1 without "\usepackage[latin1]{inputenc}".

Runaway argument
Runaway argument? {December 2004 \maketitle ! Paragraph ended before \date was complete. \par l.8

In this error, the closing curly brace has been omitted from the date. It's the opposite of the error of too many }'s, and it results in <tt>\maketitle</tt> trying to format the title page while LaTeX is still expecting more text for the date! As \maketitle creates new paragraphs on the title page, this is detected and LaTeX complains that the previous paragraph has ended but \date is not yet finished.

Underfull hbox
Underfull \hbox (badness 1394) in paragraph at lines 28--30 [][]\LY1/brm/b/n/10 Bull, RJ: \LY1/brm/m/n/10 Ac-count-ing in Busi- [94]

This is a warning that LaTeX cannot stretch the line wide enough to fit, without making the spacing bigger than its currently permitted maximum. The badness (0-10,000) indicates how severe this is (here you can probably ignore a badness of 1394). It says what lines of your file it was typesetting when it found this, and the number in square brackets is the number of the page onto which the offending line was printed. The codes separated by slashes are the typeface and font style and size used in the line. Ignore them for the moment.

This comes up if you force a linebreak, e.g., \\, and have a return before it. Normally TeX ignores linebreaks, providing full paragraphs to ragged text. In this case it is necessary to pull the linebreak up one line to the end of the previous sentence.

This warning may also appear when inserting images. It can be avoided by using the \textwidth or possibly \linewidth options, e.g. \includegraphics[width=\textwidth]{image_name}

Overfull hbox
[101] Overfull \hbox (9.11617pt too wide) in paragraph at lines 860--861 []\LY1/brm/m/n/10 Windows, \LY1/brm/m/it/10 see \LY1/brm/m/n/10 X Win-

An overfull \hbox means that there is a hyphenation or justification problem: moving the last word on the line to the next line would make the spaces in the line wider than the current limit; keeping the word on the line would make the spaces smaller than the current limit, so the word is left on the line, but with the minimum allowed space between words, and which makes the line go over the edge.

The warning is given so that you can find the line in the code that originates the problem (in this case: 860-861) and fix it. The line on this example is too long by a shade over 9pt. The chosen hyphenation point which minimizes the error is shown at the end of the line (Win-). Line numbers and page numbers are given as before. In this case, 9pt is too much to ignore (over 3mm), and a manual correction needs making (such as a change to the hyphenation), or the flexibility settings need changing.

If the "overfull" word includes a forward slash, such as " ", this should be properly typeset as " ". The use of  has the same effect as using the " " character, except that it can form the end of a line (with the following words appearing at the start of the next line). The " " character is typically used in units, such as " " character, which should not be broken over multiple lines.

The warning can also be issued when the \end{document} tag was not included or was deleted.

Easily spotting overfull hboxes in the document
To easily find the location of overfull hbox in your document, you can make latex add a black bar where a line is too wide:

Missing package
! LaTeX Error: File `paralisy.sty' not found. Type X to quit or <RETURN> to proceed, or enter new name. (Default extension: sty) Enter file name:

When you use the <tt>\usepackage</tt> command to request LaTeX to use a certain package, it will look for a file with the specified name and the filetype <tt>.sty</tt>. In this case the user has mistyped the name of the paralist package, so it's easy to fix. However, if you get the name right, but the package is not installed on your machine, you will need to download and install it before continuing. If you don't want to affect the global installation of the machine, you can simply download from Internet the necessary <tt>.sty</tt> file and put it in the same folder of the document you are compiling.

Package babel Warning: No hyphenation patterns were loaded for the language X
Although this is a warning from the Babel package and not from LaTeX, this error is very common and (can) give some strange hyphenation (word breaking) problems in your document. Wrong hyphenation rules can decrease the neatness of your document. Package babel Warning: No hyphenation patterns were loaded for (babel)               the language `Latin' (babel)               I will use the patterns loaded for \language=0 instead.

This can happen after the usage of: (see LaTeX/Internationalization)

The solution is not difficult, just install the used language in your LaTeX distribution.

Package babel Error: You haven't loaded the option X yet.
If you previously set the X language, and then decided to switch to Y, you will get this error. This may seem awkward, as there is obviously no error in your code if you did not change anything. The answer lies in the <tt>.aux</tt> file, where babel defined your language. If you try the compilation a second time, it should work. If not, delete the <tt>.aux</tt> file, then everything will work as usual.

No error message, but won't compile
One common cause of (pdf)LaTeX getting stuck is forgetting to include

Software that can check your .tex Code
There are several programs capable of checking LaTeX source, with the aim of finding errors or highlighting bad practice, and providing more help to (particularly novice) users than the built-in error messages.
 * nag (www.ctan.org/tex-archive/macros/latex/contrib/nag) is a LaTeX package designed to indicate the use of obsolete commands.
 * lacheck (www.ctan.org/tex-archive/support/lacheck) is a consistency checker intended to spot mistakes in code. It is available as source code or compiled for Windows and OS/2
 * chktex (baruch.ev-en.org/proj/chktex/) is a LaTeX semantic checker available as source code for Unix-like systems.

title: LaTeX/Errors and Warnings


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Contemporary Educational Psychology/Chapter 6: Student Motivation/Motives Related to Attributions

Motives Related to Attributions
Attributions are perceptions about the causes of success and failure. Suppose that you get a low mark on a test and are wondering what caused the low mark. You can construct various explanations for—make various attributions about—this failure. Maybe you did not study very hard; maybe the test itself was difficult; maybe you were unlucky; maybe you just are not smart enough. Each explanation attributes the failure to a different factor. The explanation that you settle upon may reflect the truth accurately—or then again, they may not. What is important about attributions is that they reflect personal beliefs about the sources or causes of success and failure. As such, they tend to affect motivation in various ways, depending on the nature of the attribution (Weiner, 2005).

Locus, Stability, and Controllability
Attributions vary in three underlying ways: locus, stability, and controllability. Locus of an attribution is the location (figuratively speaking) of the source of success or failure. If you attribute a top mark on a test to your ability, then the locus is internal; if you attribute the mark to the test’s having easy questions, then the locus is external. The stability of an attribution is its relative permanence. If you attribute the mark to your ability, then the source of success is relatively stable—by definition, ability is a relatively lasting quality. If you attribute a top mark to the effort you put in to studying, then the source of success is unstable—effort can vary and has to be renewed on each occasion or else it disappears. The controllability of an attribution is the extent to which the individual can influence it. If you attribute a top mark to your effort at studying, then the source of success is relatively controllable—you can influence effort simply by deciding how much to study. But if you attribute the mark to simple luck, then the source of the success is uncontrollable—there is nothing that can influence random chance.

As you might suspect, the way that these attributions combine affects students’ academic motivations in major ways. It usually helps both motivation and achievement if a student attributes academic successes and failures to factors that are internal and controllable, such as effort or a choice to use particular learning strategies (Dweck, 2000). Attributing successes to factors that are internal but stable or controllable (like ability), on the other hand, is both a blessing and a curse: sometimes it can create optimism about prospects for future success (“I always do well”), but it can also lead to indifference about correcting mistakes (Dweck, 2006), or even create pessimism if a student happens not to perform at the accustomed level (“Maybe I’m not as smart as I thought”). Worst of all for academic motivation are attributions, whether stable or not, related to external factors. Believing that performance depends simply on luck (“The teacher was in a bad mood when marking”) or on excessive difficulty of material removes incentive for a student to invest in learning. All in all, then, it seems important for teachers to encourage internal, stable attributions about success.

Influencing Students’ Attributions
How can they do so? One way or another, the effective strategies involve framing teachers’ own explanations of success and failure around internal, controllable factors. Instead of telling a student “Good work! You’re smart!”, try saying “Good work! Your effort really made a difference, didn’t it?” If a student fails, instead of saying “Too bad! This material is just too hard for you,” try saying “Let’s find a strategy for practicing this more, and then you can try again.” In both cases the first option emphasizes uncontrollable factors (ability, difficulty level), and the second option emphasizes internal, controllable factors (effort, use of specific strategies).

Such attributions will only be convincing, however, if teachers provide appropriate conditions for students to learn—conditions in which students’ efforts really do pay off. There are three conditions that have to be in place in particular. First, academic tasks and materials actually have to be at about the right level of difficulty. If you give problems in advanced calculus to a first-grade student, the student will not only fail them but also be justified in attributing the failure to an external factor, task difficulty. If assignments are assessed in ways that produce highly variable, unreliable marks (in the statistical sense—see Chapter 11), then students will rightly attribute their performance to an external, unstable source: luck. Both circumstances will interfere with motivation.

Second, teachers also need to be ready to give help to individuals who need it—even if they believe that an assignment is easy enough or clear enough that students should not need individual help. Readiness to help is always essential because it is often hard to know in advance exactly how hard a task will prove to be for particular students. Without assistance, a task that proves difficult initially may remain difficult indefinitely, and the student will be tempted to make unproductive, though correct, attributions about his or her failure (“I will never understand this” or “I’m not smart enough” or “It doesn’t matter how hard I study”).

Third, teachers need to remember that ability—usually considered a relatively stable factor—often actually changes incrementally over the long term. Recognizing this fact is one of the best ways to bring about actual increases in students’ abilities (Blackwell, Trzniewski, & Dweck, 2007; Schunk, Pintrich, & Meese, 2008). A middle-years student might play the trumpet in the school band at a high level of ability, but this ability actually reflects a lot of previous effort and a gradual increase in ability. A second-grade student who reads fluently and in this sense may have high current ability to read; but at some point in the distant past that same student could not read as well, and even further back he may not have been able to read at all. The increases in ability have happened at least in part because of effort. While these ideas may seem obvious, they can easily be forgotten in the classroom because effort and ability evolve according to very different time frames. Effort and its results appear relatively immediately; a student expends effort this week, this day, or even at this very moment, and the effort (if not the results) are visible right away. But ability may take longer to show itself; a student often develops it only over many weeks, months, or years.

(back to Chapter 6...)

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


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Muggles' Guide to Harry Potter/Characters/Amycus Carrow

Overview
Amycus Carrow, brother of Alecto Carrow, is a Death Eater. When we first see him, he is described as a lumpy-looking man with an odd lopsided leer.

Goblet of Fire
Alecto and Amycus are two of the Death Eaters who were summoned after Lord Voldemort's rebirth. While their names are not mentioned by Voldemort, their membership in that group is strongly implied by Snape's comments in the early chapters of Harry Potter and the Half-Blood Prince.

Half-Blood Prince
Severus Snape mentions the Carrows when he is talking to Narcissa Malfoy and Bellatrix Lestrange.

The Carrows take part in the attack on Hogwarts. Both of them are at the top of the tower when Snape kills Albus Dumbledore. Amycus showed disdain for the headmaster and wondered why Voldemort was even bothering to have him killed. During the Death Eater's escape, Amycus was seen overwhelming Ginny Weasley before being repelled by Harry. He was later ordered by Snape to retreat. He is later seen leaving the grounds along with his sister and Thorfinn Rowle.

Deathly Hallows
With Snape being appointed Headmaster, and Charity Burbage having been killed, there are vacancies for Defence Against the Dark Arts and Muggle Studies teachers. Amycus Carrow is given the post of Defence Against the Dark Arts teacher, and supervises its change of focus to remove the Defence aspects of the course. According to Neville Longbottom, under the supervision of Amycus Carrow the students were forced to perform horrible acts such as practicing the Cruciatus Curse on people who had earned detentions.

Amycus' sister Alecto, told by Lord Voldemort to expect Harry to visit Ravenclaw Tower, has herself let into the Ravenclaw common room before Harry's arrival. She is then Stunned by Luna Lovegood, who was accompanying Harry under the Invisibility Cloak. Amycus, responding to her summons (Alecto has pressed her Dark Mark, to summon Voldemort), demands to be let in, but is unable to answer the riddle posed by the eagle's-head knocker guarding the door. Having been let in by Minerva McGonagall, he finds his sister Stunned, and proposes to blame it on the students of Ravenclaw. McGonagall refuses to countenance this, Amycus spits at her, and Harry, outraged, hits Amycus with the Cruciatus curse. When he regains consciousness, McGonagall places him briefly under the Imperius curse, forcing him to give her his and his sister's wands, then lie down beside his sister, whereupon McGonagall binds them both. He takes no further part in the story.

Strengths
Amycus Carrow seems to have brute strength, and we can assume better than average skill in the Dark Arts and offensive spell casting, as shown by Voldemort assigning him the position as Dark Arts teacher and the fact that he seemed to have no trouble overpowering Ginny Weasley in a duel.

Weaknesses
Amycus is not particularly intelligent; he is unable to enter Ravenclaw tower, as he is unable to propose an answer that the eagle-head guardian will accept. His initial response seems to be brute-force, and eventually he forces Professor McGonagall to open the door for him.

Questions

 * 1) Are Amycus and Alecto Carrow loyal to the Dark Lord? Why or why not?


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Contemporary Educational Psychology/Chapter 6: Student Motivation/Motives as Self-Efficacy

Motives as Self-Efficacy
In addition to being influenced by their goals, interests, and attributions, students’ motives are affected by specific beliefs about the student’s personal capacities. In self-efficacy theory the beliefs become a primary, explicit explanation for motivation (Bandura, 1977, 1986, 1997). Self-efficacy is the belief that you are capable of carrying out a specific task or of reaching a specific goal. Note that the belief and the action or goal are specific. Self-efficacy is a belief that you can write an acceptable term paper, for example, or repair an automobile, or make friends with the new student in class. These are relatively specific beliefs and tasks. Self-efficacy is not about whether you believe that you are intelligent in general, whether you always like working with mechanical things, or think that you are generally a likeable person. These more general judgments are better regarded as various mixtures of self-concepts (beliefs about general personal identity) or of self-esteem (evaluations of identity). They are important in their own right, and sometimes influence motivation, but only indirectly (Bong & Skaalvik, 2004). Self-efficacy beliefs, furthermore, are not the same as “true” or documented skill or ability. They are self-constructed, meaning that they are personally developed perceptions. There can sometimes therefore be discrepancies between a person’s self-efficacy beliefs and the person’s abilities. You can believe that you can write a good term paper, for example, without actually being able to do so. And vice versa: you can believe yourself incapable of writing a paper, but discover that you are in fact able to do so. In this way self-efficacy is like the everyday idea of confidence, except that it is defined more precisely. And as with confidence, it is possible have either too much or too little self-efficacy. The optimum level seems to be either at or slightly above true capacity. As we indicate below, large discrepancies between self-efficacy and ability can create motivational problems for the individual.

Effects of Self-Efficacy on Students’ Behavior
Self-efficacy may sound like a uniformly desirable quality, but research as well as teachers’ experience suggests that its effects are a bit more complicated than they first appear. Self-efficacy has three main effects, each of which has both a “dark” or undesirable side and a positive or desirable side.

Choice of Tasks
The first effect is that self-efficacy makes students more willing to choose tasks where they already feel confident of succeeding. This effect is almost inevitable, given the definition of the concept of self-efficacy, it has also been supported by research on self-efficacy beliefs (Pajares & Schunk, 2002). For teachers, the effect on choice can be either welcome or not, depending on circumstances. If a student believes that he or she can solve mathematical problems, then the student is more likely to attempt the mathematics homework that the teacher assigns. Unfortunately the converse is also true. If a student believes that he or she is incapable of math, then the student is less likely to attempt the math homework (perhaps telling himself, “What’s the use of trying?”), regardless of the student’s actual ability in math.

Since self-efficacy is self-constructed, furthermore, it is also possible for students to miscalculate or misperceive their true skill, and the misperceptions themselves can have complex effects on students’ motivations. From a teacher’s point of view, all is well even if students overestimate their capacity but actually do succeed at a relevant task anyway, or if they underestimate their capacity, yet discover that they can succeed and raise their self-efficacy beliefs as a result. All may not be well, though, if students do not believe that they can succeed and therefore do not even try, or if students overestimate their capacity by a wide margin, but are disappointed unexpectedly by failure and lower their self-efficacy beliefs.

Persistence at Tasks
A second effect of high self-efficacy is to increase a persistence at relevant tasks. If you believe that you can solve crossword puzzles, but encounter one that takes longer than usual, then you are more likely to work longer at the puzzle until you (hopefully) really do solve it. This is probably a desirable behavior in many situations, unless the persistence happens to interfere with other, more important tasks (what if you should be doing homework instead of working crossword puzzles?). If you happen to have low self-efficacy for crosswords, on the other hand, then you are more likely to give up early on a difficult puzzle. Giving up early may often be undesirable because it deprives you of a chance to improve your skill by persisting. Then again (on the third hand?), the consequent lack of success because of giving up may provide a useful incentive to improve your crossword skills. And again, misperceptions of capacity make a difference. Overestimating your capacity by a lot (excessively high self-efficacy) might lead you not to prepare for or focus on a task properly, and thereby impair your performance. So as with choosing tasks, the effects of self-efficacy vary from one individual to another and one situation to another. The teacher’s task is therefore twofold: first, to discern the variations, and second, to encourage the positive self-efficacy beliefs. Table 6-2 offers some additional advice about how to do this.

Response to Failure
High self-efficacy for a task not only increases a person’s persistence at the task, but also improves their ability to cope with stressful conditions and to recover their motivation following outright failures. Suppose that you have two assignments—an essay and a science lab report—due on the same day, and this circumstance promises to make your life hectic as you approach the deadline. You will cope better with the stress of multiple assignments if you already believe yourself capable of doing both of the tasks, than if you believe yourself capable of doing just one of them or (especially) of doing neither. You will also recover better in the unfortunate event that you end up with a poor grade on one or even both of the tasks.

That is the good news. The bad news, at least from a teacher’s point of view, is that the same resilience can sometimes also serve non-academic and non-school purposes. How so? Suppose, instead of two school assignments due on the same day, a student has only one school assignment due, but also holds a part-time evening job as a server in a local restaurant. Suppose, further, that the student has high self-efficacy for both of these tasks; he believes, in other words, that he is capable of completing the assignment as well as continuing to work at the job. The result of such resilient beliefs can easily be a student who devotes less attention to school work than ideal, and who even ends up with a lower grade on the assignment than he or she is capable of.

Learned Helplessness and Self-Efficacy
If a person’s sense of self-efficacy is very low, he or she can develop learned helplessness, a perception of complete lack of control in mastering a task. The attitude is similar to depression, a pervasive feeling of apathy and a belief that effort makes no difference and does not lead to success. Learned helplessness was originally studied from the behaviorist perspective of classical and operant conditioning by the psychologist Martin Seligman (1995). The studies used a somewhat “gloomy” experimental procedure in which an animal, such as a rat or a dog, was repeatedly shocked in a cage in a way that prevented the animal from escaping the shocks. In a later phase of the procedure, conditions were changed so that the animal could avoid the shocks by merely moving from one side of the cage to the other. Yet frequently they did not bother to do so! Seligman called this behavior learned helplessness.

In people, learned helplessness leads to characteristically ways of dealing with problems. They tend to attribute the source of a problem to themselves, to generalize the problem to many aspects of life, and to see the problem as lasting or permanent. More optimistic individuals, in contrast, are more likely to attribute a problem to outside sources, to see it as specific to a particular situation or activity, and to see it as temporary or time-limited. Consider, for example, two students who each fail a test. The one with a lot of learned helplessness is more likely to explain the failure by saying something like “I’m stupid; I never perform well on any schoolwork, and I never will perform well at it.” The other, more optimistic student is more likely to say something like “The teacher made the test too hard this time, so the test doesn’t prove anything about how I will do next time or in other subjects.”

What is noteworthy about these differences in perception is how much the more optimistic of these perspectives resembles high self-efficacy and how much learned helplessness seems to contradict or differ from it. As already noted, high self-efficacy is a strong belief in one’s capacity to carry out a specific task successfully. By definition therefore self-efficacy focuses attention on a temporary or time-limited activity (the task), even though the cause of successful completion (oneself) is “internal.” Teachers can minimize learned helplessness in students, therefore, by encouraging their self-efficacy beliefs. There are several ways of doing this, as we explain next.

Sources of Self-Efficacy Beliefs
Psychologists who study self-efficacy have identified four major sources of self-efficacy beliefs (Pajares & Schunk, 2001, 2002). In order of importance they are Fortunately the first three can be influenced by teachers directly, and even the fourth can sometimes be influenced indirectly by appropriate interpretive comments from the teacher or others.
 * 1) prior experiences of mastering tasks,
 * 2) watching others’ mastering tasks,
 * 3) messages or “persuasion” from others, and
 * 4) emotions related to stress and discomfort.

Prior Experiences of Mastery
Not surprisingly, past successes at a task increase students’ beliefs that they will succeed again in the future. The implication of this basic fact means that teachers need to help students build a history of successes. Whether they are math problems, reading assignments, or athletic activities, tasks have to end with success more often than with failure. Note, though, that the successes have to represent mastery that is genuine or competence that is truly authentic. Success at tasks that are trivial or irrelevant do not improve self-efficacy beliefs, nor does praise for successes that a student has not really had (Erikson, 1968/1994).

As a practical matter, creating a genuine history of success is most convincing if teachers also work to broaden a student’s vision of “the past.” Younger students (elementary-age) in particular have relatively short or limited ideas of what counts as “past experience”; they may go back only a few occasions when forming impressions of whether they can succeed again in the future (Eccles, et al., 1998). Older students (secondary school) gradually develop longer views of their personal “pasts,” both because of improvements in memory and because of accumulating a personal history that is truly longer. The challenge for working with any age, however, is to insure that students base self-efficacy beliefs on all relevant experiences from their pasts, not just on selected or recent experiences.

Watching Others’ Experiences of Mastery
A second source of efficacy beliefs comes from vicarious experience of mastery, or observing others’ successes (Schunk & Zimmerman, 1997). Simply seeing someone else succeed at a task, in other words, can contribute to believing that you, too, can succeed. The effect is stronger when the observer lacks experience with the task and therefore may be unsure of his or her own ability. It is also stronger when the model is someone respected by the observer, such as a student’s teacher, or a peer with generally comparable ability. Even under these conditions, though, vicarious experience is not as influential as direct experience. The reasons are not hard to imagine. Suppose, for example, you witness both your teacher and a respected friend succeed at singing a favorite tune, but you are unsure whether you personally can sing. In that case you may feel encouraged about your own potential, but are likely still to feel somewhat uncertain of your own efficacy. If on the other hand you do not witness others’ singing, but you have a history of singing well yourself, it is a different story. In that case you are likely to believe in your efficacy, regardless of how others perform.

All of which suggests that to a modest extent, teachers may be able to enhance students’ self-efficacy by modeling success at a task or by pointing out classmates who are successful. These strategies can work because they not only show how to do a task, but also communicate a more fundamental message, the fact that the task can in fact be done. If students are learning a difficult arithmetic procedure, for example, you can help by demonstrating the procedure, or by pointing out classmates who are doing it, or by pointing out classmates who are doing it. Note, though, that vicarious mastery is helpful only if backed up with real successes performed by the students themselves. It is also helpful only if the “model classmates” are perceived as truly comparable in ability. Overuse of vicarious models, especially in the absence of real success by learners, can cause learners to disqualify a model’s success; students may simply decide that the model is “out of their league” in skills and is therefore irrelevant to judging their own potential.

Social Messages and Persuasion
A third source of efficacy beliefs are encouragements, both implied and stated, that persuade a person of his or her capacity to do a task. Persuasion does not create high efficacy by itself, but it often increases or supports it when coupled with either direct or vicarious experience, especially when the persuasion comes from more than one person (Goddard, Hoy, & Hoy, 2004).

For teachers, this suggests two things. The first, of course, is that encouragement can motivate students, especially when it is focused on achievable, specific tasks. It can be motivating to say things like “I think you can do it” or “I’ve seen you do this before, so I know that you can do it again.” But the second implication is that teachers should arrange wherever possible to support their encouragement by designing tasks at hand that are in fact achievable by the student. Striking a balance of encouragement and task difficulty may seem straightforward, but sometimes it can be challenging because students can sometimes perceive teachers’ comments and tasks quite differently from how teachers intend. Giving excessive amounts of detailed help, for example, may be intended as support for a student, but be taken as a lack of confidence in the student’s ability to do the task independently.

Emotions Related to Success, Stress or Discomfort
The previous three sources of efficacy beliefs are all rather cognitive or “thinking oriented,” but emotions also influence expectations of success or failure. Feeling nervous or anxious just before speaking to a large group (sometimes even just a class full of students!) can function like a message that says “I’m not going to succeed at doing this,” even if there is in fact good reason to expect success. But positive feelings can also raise beliefs about efficacy. When recalling the excitement of succeeding at a previous, unrelated task, people may overestimate their chances of success at a new task with which they have no previous experience, and are therefore in no position to predict their efficacy.

For teachers, the most important implication is that students’ motivation can be affected when they generalize from past experience which they believe, rightly or wrongly, to be relevant. By simply announcing a test, for example, a teacher can make some students anxious even before the students find out anything about the test—whether it is easy or difficult, or even comparable in any way to other experiences called “tests” in their pasts. Conversely, it can be misleading to encourage students on the basis of their success at past academic tasks if the earlier tasks were not really relevant to requirements of the new tasks at hand. Suppose, for example, that a middle-years student has previously written only brief opinion-based papers, and never written a research-based paper. In that case boosting the student’s confidence by telling him that “it is just like the papers you wrote before” may not be helpful or even honest.

A Caution: Motivation as Content versus Motivation as Process
A caution about self-efficacy theory is its heavy emphasis on just the process of motivation, at the expense of the content of motivation. The basic self-efficacy model has much to say about how beliefs affect behavior, but relatively little to say about which beliefs and tasks are especially satisfying or lead to the greatest well-being in students. The answer to this question is important to know, since teachers might then select tasks as much as possible that are intrinsically satisfying, and not merely achievable. Another way of posing this concern is by asking, “Is it possible to feel high self-efficacy about a task that you do not enjoy?” It does seem quite possible for such a gap to exist. As a youth, for example, one of us contributors (KelvinLeeSeifert) had considerable success with solving mathematics problems in high school algebra, and expended considerable effort doing algebra assignments as homework. Before long, he had developed high self-efficacy with regard to solving such problems. But Kelvin never really enjoyed solving the algebra problems, and later even turned away permanently from math or science as a career (much to the disappointment of his teachers and family). In this case self-efficacy theory nicely explained the process of his motivation—Kelvin’s belief in his capacity led to persistence at the tasks. But it did not explain the content of his motivation—his growing dislike of the tasks. Accounting for such a gap requires a different theory of motivation, one that includes not only specific beliefs, but “deeper” personal needs as well. An example of this approach is self-determination theory, where we turn next.


text:
Data Coding Theory/Shannon capacity

Channels
A channel is a communications medium, through which data can flow through. In a wireless network, the channel is the open space between the sender and the receiver through with the electromagnetic waves travel. In a wired network, the channel is the wire through with the electrical signals flow.

Signal to Noise Ratio
Data flowing through a channel is subjected to outside noise interference. In a wireless system, this interference can be a competing transmittor, or even natural phenomena such as lightning or solar radiation. These same kinds of interference can affect wired transmissions as well.

The ratio, in dB (decibels) of the transmitted information power to the noise power in the received signal is known as the signal to noise ratio. The signal to noise ratio, abbreviated "SNR", is an important metric to learn when studying a transmission network, because it affects how much data can be sent and at what speed. If we have a signal with energy E, and a noise density of N, we calculate the SNR as:

 * $$SNR = 10 \log_{10}\left(\frac{E}{N}\right)$$

Likewise, if we have a signal with an amplitude of A, and a noise with variance σ, we calculate the SNR as:

 * $$SNR = 10\log_{10}\left(\frac{A^2}{\sigma^2}\right)$$

The higher the SNR, the more faithful the received signal will be to the sent signal. The lower the SNR, the more likely the received signal is going to contain errors. We won't cover SNR in too much detail in this book. However, the SNR is a very important quantity in a communications system, and there are classes of codes that are designed to help reduce errors in a channel with a low SNR.

Bandwidth
Bandwidth is a measurement of a communication's channel, and determines what frequency ranges are transmitted faithfully through the channel, and which ranges are not. We don't need to discuss bandwidth in any detail in this book, but suffice it to say that it is an important quality of a communications channel.

Shannon's Channel Capacity
The Shannon Channel Capacity is a formula that relates the bandwidth of a channel, the channel's SNR, and the bit rate.

 * $$C = W \log_2 (1 + SNR)$$

The channel capacity is the bit rate at which data can be sent along a channel with a negligible error rate. Attempting to send bits faster than this rate will increase the error rate beyond a negligible value. This will have large negative effects on our communications system. Notice that for a fixed bandwidth, as SNR decreases, the bitrate must also decrease.

Ramifications of Channel Capacity
Because of Shannon's Channel Capacity, we can see a few important facts. The first of which is, the more noise a channel has, the slower our bitrate needs to be. This means that if we want to send data at or above the channel capacity, we will need to have a robust error checking and correcting mechanism.

What we can also see is that for a fixed SNR, more bandwidth means a faster data rate.

In short, to send more information over a channel more quickly, we need to:
 * Increase the SNR
 * Increase the bandwidth
 * Use better coding and error correcting.

title: Data Coding Theory/Shannon capacity


text:
Data Coding Theory/Modulo-2 Arithmetic

Modulo
The modulo operation, commonly expressed as a "%" operator, is a useful operation in data coding. Modulo is the remainder of a division operation between two numbers. For instance, if we divide 10 by 3 and we don't calculate decimal points, we get:

 * $$\frac{10}{3} = 3$$

And the remainder would be:

 * $$ 10 \% 3 = 1$$

In division, we typically have the equation:

 * $$s = n \times d + r$$

Where s is our dividend, d is our divisor, n is our quotient, and r is the remainder. From this equation, we have two operations:

 * $$s \div d = n$$
 * $$s \% d = r$$

Notice from these equations that r must always be smaller than d.

Modulo-2 Arithmetic
Modulo-2 arithmetic is an arithmetic system where every result is taken modulo-2. Here are some examples:

 * $$(10 + 5)_{\%2} = 1$$

 * $$(2 \times 8)_{\%2} = 0$$

In short, the result of the operation is 1 if the result is odd, and 0 if the result is even. Since we are dealing with individual bits in our data coding, most of our operands will be a 1 or a 0. So long as our operands are 1 or 0, and our results are modulo 2, all the number we write should be 1 or 0.

A common application of modulo-2 arithmetic is in digital circuitry, where logic operations are all performed modulo-2.

Modulo-2 operators
In our modulo-2 arithmetic system, we define new operators. These operators are frequently very similar to boolean logical operators, so we will discuss those here too.

 * Add:To add two numbers, we take the modulo-2 of the result. Here is a truth table for an add operation:
 * {| class="wikitable"

!+ !!0!!1 !0 !1
 * 0
 * 1
 * 1
 * 0
 * }
 * If you are familiar with boolean logic, you will see that addition is identical to the xor operation. Because of this, we will use the terms "add" and "xor" interchangeably, and we will denote the modulo-2 addition operation with a "circle-plus":
 * $$1 \oplus 1 = 0$$

 * Multiply:Multiplication in modulo 2 happens normally, and no new operator needs to be defined. Here is the truth table for a multiplication operation:
 * {| class="wikitable"

!×!!0!!1 !0 !1
 * 0
 * 0
 * 0
 * 1
 * }
 * This is exactly the same as the boolean "and" operation. We will use the words "multiplication" and "and" interchangeably.

Subtraction and division operations are rare in data coding, so we won't discuss them here.

title: Data Coding Theory/Modulo-2 Arithmetic


text:
How To Build A Teardrop Trailer/Walls and Doors

Side Walls
At this point in your build, you should have an assembled trailer frame (less lights, fenders, and fender braces), with a nice wooden bed bolted in position. The bottom of the bed is protected with roofing tar.

Polyurethane glue is going to be an important part of the trailer construction. It fills gaps, is not brittle (like yellow wood glue) and is extremely binding and strong. So strong that the force applied to a piece of 2x2 pine wood which was polyurethane glued to cabinet grade .75" plywood for only 30 minutes actually took the first ply off the wood, but not before splitting the plywood down the middle.

The difference between this teardrop trailer body and just a simple box is that the body walls, roof and bed will be bonded together with this polyurethane glue, in essence creating a monocoque. In addition, the teardrop shape of the roof line increases the strength over a square box because forces are transferred around the curves down to the base.

Profiles
You need to spend some time and pick out a profile for your teardrop trailer. There are many variations of profiles and some have names like "benroy", "modern" but there are really only two classes of sidewalls - those which come down perpendicular to the bed and those which curve out beyond the front of the bed then curve back to it. And these are used in combination also. The modern profile has both front and back curving out and back like an airplane wing. The benroy front and rear meet perpendicular to the bed. Others use the out and back curve on the front and meet the bed perpendicular at the rear. Yet others do the opposite.

You really should take the time to explore what you like and design your own variation. The profile of the teardrop trailer is the most distinctive and artistic part. It defines the trailer and can either make onlookers say "Wow!" or "Ugh!".

One other thing, the cabinet grade plywood has a good side and a bad side. Its up to you but you should really put the good side out unless you are going to skin the trailer or paint it. This book doesn't cover skinning or painting. Our "simple" trailer is a "woodie" that will be covered with marine grade urethane varnish.

Also when you are drawing your profile on the wood you should draw it on the "inside", because a sabor-saw cuts on the upstroke and the exit side of the cutting blade is the side that has the rough edges. You want the "outside" to have the cleanest cut edges.

Door Shape
You also need to decide on a door shape. Again there are many variations. Some are completely square. Some have a straight edge on hinge side and a straight edge across the bottom, and have a long side arch opposite the hinge side. Some have a simple arched top or rounded corners. Other variations exist and are possible.

You need to put some thought into the door shape, the hinge and how you are going to place a door seal. The door shape will have an impact on the type of hinge you use and whether you can seal from the outside or not.

Hinge styles

 * There are three styles of hinges commonly used for teardrop trailers.
 * Regular house style hinges
 * A piano hinge.
 * Gate hinges

A regular house style hinge requires that a door jam be constructed deep enough to accommodate it. On the plus side there is nothing custom or experimental about it. You create the door and jam just like on a house.

Piano hinges are common on teardrop trailers. One issue with a piano hinge is that you need to buy one that has a galvanized pin. The kind found at the hardware stores usually have a plain steel pin which will rust. There are also nylon piano hinges that have no pin at all. The nylon is narrowed in the center to form the bending point.

Gate hinges are another option and can easily be attached without the need for an accommodating jam. These hinges simply bolt on. They also have an advantage over the previous two in that the pivot of the hinge can easily be offset or mounted away from the edge of the door. However, one issue with gate hinges is that you need to find ones with nylon bushings. Ones without nylon bushings are too sloppy to hold the door in a precise position for closing.

Door design considerations

 * If you have a square door you have the option of constructing it just like the door of your house, with a home style door jam, seals and door knob. The downside is that its square and not very stylish, however, some clever builders will attach a perimeter moulding around the outside of the door and arch the moulding to beautify the profile.

 * One popular door style is the side arch style. It is mounted with a piano hinge on the straight side from top to bottom. Then a seal is placed in the pinch area behind the hinge and a perimeter moulding is attached either around the rest of the outside of the door perimeter or around the complete inside door opening parameter as a seal seat.

 * The other styles of doors can increase complexity quite a bit. Basically any door style that does not have a straight edge all the way from the top of the door to bottom of the door on the hinge side is problematic.  The reason is that the seal surface behind the hinge mechanically creates a "pitch" motion where as the surface around the rest of the perimeter simply contacts the surface.  So for example if you have rounded corners then you have a situation where the motion of the closing door actually traverses the surface sideways on the seal and will tend to push the seal out of position.

Rain
It is also helpful to understand how rain will behave on the trailer. Rain will hit the body of the trailer first and travel along the body surface. Driving down the road at 70 mph sets up hurricane force wind conditions. No seals are designed to operate under those conditions. If you look at door and trunk seals on a car you will see that the solution involves designing a channel for the main stream of water to flow around the door harmlessly and use the seal only to stop any extraneous water streams.

So the rules are to design so that openings are flush with the sides and to keep seals out of the main stream of water flow as much as possible. This means if you have an exterior perimeter moulding on the door you may need to have a perimeter "guard" on the body adjacent to the door. Some builders will just put a deflector over the top of the door and down the front.

Its also important to put things into perspective. How much time and effort are you going to put into trying to make the doors absolutely watertight? Its your decision depending on how much effort and money you are putting into the rest of the trailer. However it may be reasonable to consider the home-made teardrop trailer for what it is - one step up from tent camping and thus you really should treat it like a tent. Meaning that after a camping trip, just like a tent, you better clean it out, open it up, and make sure its clean and dry before you pack it away. And if you need to use a towel to catch a few drops while on vacation - don't sweat it.

Our Simple Teardrop
For our simple teardrop the profile attaches perpendicular to the bed. We are also using .75 inch cabinet grade plywood for our sidewalls. Lay the plywood down on the saw horses and draw out your profile and door opening.

You can make compasses by simply cutting a long strip of wood, drilling a hole in one end snug enough to hold a pencil firmly and putting a drywall screw through the other end at the right radius.

The author's teardrop used a 20 inch radius for the front and a 38 inch radius for the rear. The radius for the door corners is 6 inches.

Do not use a radius smaller than 20 inches. In fact, for the front you should choose a larger radius (25 or even 30 inches). The reason is that the top will be covered with 5.2mm luan (birch plywood) and the 20 inch radius required that the screws be started and rotationally and incrementally tightened in order to avoid breaking the plywood. A larger radius will help you avoid this headache.

Once you have your doors and profile drawn, you can start cutting. Use a decent saber saw with a new blade stand comfortably, wear your safety glasses and take your time. The wood cut out for the door opening is used for the door, so you don't want to drill a hole to start the cut. The saber saw cut can be started by angling the saw up, turning the saw on, and very slowly and carefully lower it onto the cutting line you have drawn. Practice on a scrap piece to get a feel for it. After cutting, sand the edges of the plywood.

>>Next:Assembling the Body


text:
Talk:Tcl Programming/Introduction

"Tcl was created in 1988 by John Ousterhout and is distributed under a BSD style license (which allows you everything GPL does, plus commercial use). The current stable version, in September 2006, is 8.4.14, while the alpha of its successor is 8.5a5." -- the GPL lets you use it for commercial purposes but must stay under the GPL 172.135.73.10 01:23, 25 August 2007 (UTC)

This has since been rewritten to be more precise. Suchenwi (discuss • contribs) 09:03, 25 November 2012 (UTC)

wikimedia have a source highlighting extention
shall use it?! --Hoxel 14:47, 15 November 2007 (UTC)

I think this coloring scheme is, like many others, butt ugly; and it seems to suggest semantic differences between words that mostly are not really there. Unlike other languages with reserved words and restrained syntax, Tcl is very relaxed here, e.g. in the command set set set the first word is the command name, the second a variable name, the third a string constant (well, all three are string constants after all). A syntax colorizer might know that due to hard-learned knowledge, but it'll then fail on user-defined commands, for which of course the same liberty holds.

When I do coloring in Tcl editors, I refrain myself to painting the top line of proc's blue, and comments in red... but mostly I'm happy enough with just black on white all the way. And this is a Wiki*book*, isn't it? Suchenwi 21:23, 15 November 2007 (UTC)

Error in section "Quick summary"
In the mentioned section of this page, it says: "In quoted words, substitutions can occur before the command is called: $[A-Za-z0-9_]+ substitutes the value of the given variable." If I understand this sentence right, it says that variable names must be composed of alphanumerical characters or underscore. This is wrong: Tcl does not know such limitations! A variable name can contain any character: % set :-) foobar foobar % puts ${:-)} foobar %

Thanks for pointing that out - I have clarified it with another example. Suchenwi (discuss • contribs) 09:03, 25 November 2012 (UTC)

Not Objective.
No References.

Answers it's own header Titles with things such as 'Good Question.'

title: Talk:Tcl Programming/Introduction


text:
User talk:Khutsch

Come introduce yourself at the new users page. If you have any questions, you can ask there or contact me personally.

Hello
Hi Khutsch! Thanks for your work on the Reptiles honor. If you have any questions about this book, please don't hesitate to ask me. You can reach me on my talk page. --Jomegat 02:17, 25 August 2007 (UTC)

title: User talk:Khutsch


text:
User:JohnManuel

Welcome to my page

title: User:JohnManuel


text:
Basic Algebra/For Contributors

Welcome to the Basic Algebra project!

Each lesson has 5 sections:
 * Vocabulary - simple explanations of new terms.
 * Lesson - What does this new skill let us do?
 * Example Problems - three example problems worked out in detail.
 * Practice Games - links to outside games on the internet that reinforce skills needed for this new skill
 * Practice Problems - in three sections (easy, medium, hard). Please list the question, then give the answer in parentheses. Example 2x=6: (x=3)

Remember: All textbooks have many, many problems in common. Don't worry if the problem you add is in a copyrighted textbook. No one owns 2x = 16, for example. Be sure that you do not copy lists of problems. Make sure all word problems you give are completely original as far as subject matter is concerned. Please be sure the subject of your word problem is a BE850 word.

We assume that these students are ready for algebra. We do include a review of basic mathematics ideas in order to direct the students towards integrating their prior math knowledge, especially math vocabulary. This is a standard practice in algebra textbooks.

Also, please log in when you contribute so we can contact each other. Thanks!

title: Basic Algebra/For Contributors


text:
Basic Algebra/Introduction to Basic Algebra Ideas/Chapter Review

Lesson 1. Simple Operations
An operation is a thing you do to numbers. You use signs like: +, –, ×, or ÷ for operations. The Equals Sign is not an operation.

 * Adding
 * Adding is a way to put two numbers together.

 * 1 + 2 = 3

 * Subtracting
 * Subtracting is a way of taking a number out from another number.

 * 2 – 1 = 1

 * Multiply
 * Multiplying is a way of adding a number many times

 * 3 × 2 = 6

 * Dividing
 * Dividing is a way of subtracting a number many times.

 * 6 ÷ 2 = 3

 * Example Problems:

 * 2 + 1 = 3
 * 8 + 2 = 10
 * 8 – 4 = 4
 * 5 – 2 = 3
 * 6 × 2 = 12
 * 2 × 3 = 6
 * 12 ÷ 6 = 2
 * 4 ÷ 2 = 2

Back to lesson

Lesson 2. Exponents and Powers
Exponent is the number on the top that shows.

Base is the number to be multiplied by itself.

 * Example Problems:

 * 62 = 36
 * 23 = 8
 * 42 = 16
 * 53 = 125
 * 24 = 16

Back to lesson

Lesson 3. Order of Operations
Math problems are done in this order from top to bottom:

 * Parenthesis
 * Exponent ^
 * Multiply ×, Divide ÷ (Left to Right)
 * Add +, Subtract – (Left to Right)

 * Example Problem:

Back to lesson

Lesson 4. Working With Negative Numbers
A positive number is a number more than zero.

A negative number is a number less than zero.

 * Example Problems:

 * 6 + (–3) = 3
 * 3 + (–9) = –6
 * –4 × 4 = -16
 * 4 × (–9) = -36
 * –2 × (–4) = 8

Back to lesson

Lesson 5. Solving Equations Using Properties of Mathematics
It is very important to show math in the simplest way. For example, 5/10 is the same as 1/2, but 1/2 is better because it is easier to understand. The simplest answer is usually the best.

 * Example Problems
 * Find $$x$$ when $$y = 9$$

Back to lesson


text:
Category:User uk

eo:kategorio:uzanto uk it:Categoria:Utenti uk ja:Category:User uk

title: Category:User uk


text:
Category:User he

am:Category:User he an:Categoría:Usuario he be-x-old:Катэгорыя:Вікіпэдыйцы, якія ведаюць мову he br:Rummad:Implijer he lad:Category:User he nn:Kategori:Brukar he ksh:Saachjrupp:Wikipedia:Medmaacher kann Hebräjėsch yi:קאַטעגאָריע:באַניצער he zh-yue:Category:User he it:Categoria:Utenti he pt:Categoria:Usuário he ru:Категория:User he

title: Category:User he


text:
User:Masoris

 * wikipedia:User:Masoris

title: User:Masoris


text:
XQuery/Gotchas

generalised equals
= is a sequence comparison which is true if the intersection is not empty. Thus:

(1, 2, 3) = (3, 4, 5)

and 3 = (3, 4, 5)

but there are some oddities. For example = is false, as is    !=

The operator eq is used to compare values only.

Arithmetic operators
The minus sign needs space around it since $x-3 is a valid variable name which is not the same as $x - 3.

Matching brackets etc
Check carefully for matching single and double quotes, round and square brackets and curly braces. The java client will show the matching bracket, but errors are often poorly diagnosed by XQuery compilers.

Binding

The abbreviated form in which multiple binding statements can be separated by a comma:

let $x := 3 let $y := 4 let $x := "fred" Abbreviates to

let $x := 3, $y := 4, $x := "fred"

is convenient but can lead to errors when code is amended. Consider avoiding this syntax.

Conditional expression
The conditional expression must have the else part. Return the empty sequence if one alternative is not required:

if ($x = 4) then "Four" else

Sorting
'Order by' sorts numbers as text order by $c/population

To get it sorted as a number, you have to use the number function

order by number($C/population)

or cast to a number type

order by xs:integer($c/population)

or order by $c/population cast as xs:integer

XML construction
You can build XML by simply starting a tag. These tags are really XQuery expression operators. However, this puts you in a lexical scope where everything is XML and curly braces then switch back to normal XQuery (and an open tag will then switch back to XML). Escape curly braces with double braces.

Note the toggling between XQuery and XML construction modes:

let $a:= "bob" let $b:= "jane" let $ab := ($a, $b) return { for $person in $ab return {$person} }

Comments
Comments in XQuery use (: ... :) whereas comments in XML use

It is easy to use the wrong kind in the wrong context, particularly XQuery comments in constructed XML.

 (: a comment :)  makes the comment the text part of an XML element.

let
let statements are part of a FLWOR expression and can't appear alone. XQuery is a functional language and let statements are only temporary bindings of names to expressions.

let $x := 5 return $x

function result
return is not required in functions. It is part of a FLWOR statement and not a statement in itself (like let). So it is not required and not allowed if there is no for or let.

declare function local:sum($a, $b) { $a + $b }

or

declare function local:sum($a, $b) { let $c := $a + $b return $c } but not declare function local:sum($a, $b) { return $a + $b }

Rounding with double and floats
You might be surprised at that the result of the following:

is 6.30000000000001 This is because number casts the values to double and the double precision numbers round values using an algorithm that is statistically close when using many numbers but fails in specific test cases like this. This is not technically an error and other systems (Scala, ruby, python etc.) will also generate the same errors. The way around this is to not use the number function, but cast to an xs:decimal.

title: XQuery/Gotchas


text:
Physical Activity/Planche

A planche is a skill learned in Gymnastics where the goal is to hold the body in a position that is parallel to the ground while keeping the arms straight. When performed correctly, the body should appear to be floating. The skill requires an extreme amount of strength and a minimal amount of balance. Bending the arms, back, or the legs is incorrect form.

In order to progress to a full planche (Where the body is completely straight with the legs kept together) there are easier forms of planche to practice.

In order to gain the amount of balance you will need a frog stand is recommended.

After the minimal balance is learned, a tuck planche can be practiced. In this position the performer keeps their legs as close to their chest as possible (bending the back) while only touching the ground with their hands. Arms must be kept straight. Bending the arms will not train the correct muscles for a full planche.

After becoming comfortable in a tuck planche, the advanced tuck planche is the next step. This is the same position but the back is kept straight to increase the difficulty. (Legs are forced away from the body by becoming straight.)

The next step is the straddle planche. The back should be straight and the legs are now straight as well but kept separated from each other. (As if in the splits position but off of the ground staying parallel to the floor.)

The last step is the full planche where the legs are brought together. The is the most difficult form.

There are multiple ways of touching the floor with the hands. For people with flexible wrists, keeping the palms touching the ground while leaning forward would be easiest. For those who have less flexible wrists, going up unto the finger tips is easier because the back of the hand faces up instead of backwards. The last position is to have the hands placed backwards with the palms flat which can make balancing more difficult.

After mastering any of the positions, push up motions can be added for intense motion workouts.

title: Physical Activity/Planche


text:
User talk:YordanGeorgiev

Come introduce yourself at the new users page. If you have any questions, you can ask there or contact me personally. -- Herby talk thyme 08:43, 25 August 2007 (UTC)

EN wikibooks
Hi - please note this in en wikibooks and as such it is hard to see where your foreign languages pages will fit it. They may be considered to be outside our project scope. Thanks -- Herby talk thyme 08:43, 25 August 2007 (UTC)

Thanks ,

I am moving it to the bulgarian section of wikibooks ... after 1 hour. YordanGeorgiev 08:47, 25 August 2007 (UTC)

Hi, To any admin of the en.wikibooks. Please remove the whole book ... I moved it to the Bulgarian section of wikibooks, where it belongs .... Once again sorry !!!!
 * Done. --Az1568(Talk) 09:32, 25 August 2007 (UTC)

title: User talk:YordanGeorgiev


text:
Cookbook:Sharbat bil Loz

| Beverages | Iranian Cuisine

Sharbat bil loz is an Iranian beverage.

Ingredients

 * 4 cups blanched almonds
 * 4 cups water
 * 3 cups sugar (optional, it is healthier without sugar)
 * ¼ cup orange blossom water (or rosewater)

Procedure

 * 1) Grind the almonds finely in blender.
 * 2) Add the water and continue to grind.
 * 3) Strain the liquid through a sieve lined with cheesecloth, reserving the liquid.
 * 4) When drained, squeeze the remaining pulp to extract as much liquid as possible. Discard the pulp.
 * 5) Pour into a heavy saucepan, then stir in the sugar (optional).
 * 6) Boil, stirring constantly, then lower the heat and simmer very gently for 5–10 minutes.
 * 7) Turn off the heat, add the orange flower water, and let the syrup cool.
 * 8) To serve, pour ¼ cup of syrup into a glass, add ice water, and stir well.

Notes, tips, and variations

 * Instead of throwing away the almond pulp, you can mix it into almond agar jelly.

title: Cookbook:Sharbat bil Loz


text:
XQuery/eXist demo server

The sample scripts are executed on a server running a release of the eXist XML database. This server is based in the Faculty of Computing, Engineering and Mathematical Sciences at the University of the West of England, Bristol.

The demo server is currently running release 1.4.0

We appreciate the use of this free server and hope you use its resources respectfully.

title: XQuery/eXist demo server


text:
Template:Miskito/Nav

Navigation template for Miskito language course
 * parameter 1: previous page/lesson (format: "Lesson X", "Introduction"...)
 * parameter 2: next page/lesson (format: "Lesson X", "Introduction")

title: Template:Miskito/Nav


text:
Contemporary Educational Psychology/Chapter 6: Student Motivation/Motivation as Self-Determination

Motivation as Self-Determination
Common sense suggests that human motivations originate from some sort of innate “need.” We all think of ourselves has having various “needs”—a need for food, for example, or a need for companionship—that influence our choices and activities. This same idea also forms part of some theoretical accounts of motivation, though the theories differ in the needs that they emphasize or recognize. In Chapter 3, for example, we talked about Maslow’s hierarchy of needs as an example of motivations that function like needs that influence long-term personal development. According to Maslow, individuals must satisfy physical survival needs before they seek to satisfy needs belonging, they satisfy belonging needs before esteem needs, and so on. In theory, too, people have both deficit needs and growth needs, and the deficit needs must be satisfied before growth needs can influence behavior (Maslow, 1970). In Maslow’s theory, as in others that use the concept, a need is a relatively lasting condition or feeling that requires relief or satisfaction and that tends to influence action over the long term. Some needs may decrease when satisfied (like hunger), but others may not (like curiosity). Either way, needs differ from the self-efficacy beliefs discussed earlier, which are relatively specific and cognitive, and affect particular tasks and behaviors fairly directly.

A recent theory of motivation based on the idea of needs is self-determination theory, proposed by the psychologists Edward Deci and Richard Ryan (2000), among others. The theory proposes that understanding motivation requires taking into account three basic human needs:

 * autonomy—the need to feel free of external constraints on behavior
 * competence—the need to feel capable or skilled, and
 * relatedness—the need to feel connected or involved with others.

Note that these needs are all psychological, not physical; hunger and sex, for example, are not on the list. They are also about personal growth or development, not about deficits that a person tries to reduce or eliminate. Unlike food (in behaviorism) or safety (in Maslow’s hierarchy), you can never get enough of autonomy, competence, or relatedness. You (and your students) will seek to enhance these continually throughout life.

The key idea of self-determination theory is that when persons (such as you or one of your students) feels that these basic needs are reasonably well met, they tend to perceive their actions and choices to be intrinsically motivated or “self-determined.” In that case they can turn their attention to a variety of activities that they find attractive or important, but that do not relate directly to their basic needs. Among your students, for example, some individuals might read books that you have suggested, and others might listen attentively when you explain key concepts from the unit that you happen to be teaching. If one or more basic needs are not met well, however, people will tend to feel coerced by outside pressures or external incentives. They may become preoccupied, in fact, with satisfying whatever need has not been met and thus exclude or avoid activities that might otherwise be interesting, educational, or important. If the persons are students, their learning will suffer.

Self-Determination and Intrinsic Motivation
In proposing the importance of needs, then, self-determination theory is asserting the importance of intrinsic motivation, an idea that has come up before in this book (see especially Chapter 2, about learning theory), and that will come again later (see especially Chapter 7, about instructional planning). The self-determination version of intrinsic motivation, however, emphasizes a person’s perception of freedom, rather than on the presence or absence of “real” constraints on action. Self-determination means a person feels free, even if the person is also operating within certain external constraints. In principle, a student can experience self-determination even if the student must, for example, live within externally imposed rules of appropriate classroom behavior. To achieve a feeling of self-determination, however, the student’s basic needs must be met—needs for autonomy, competence, and relatedness. In motivating students, then, the bottom line is that teachers have an interest in helping students to meet their basic needs, and in not letting school rules or the teachers’ own leadership styles interfere with or block satisfaction of students’ basic needs.

“Pure” self-determination may be the ideal for most teachers and students, of course, but the reality is usually different. For a variety of reasons, teachers in most classrooms cannot be expected to meet all students’ basic needs at all times. One reason is the sheer number of students, which makes it impossible to attend to every student perfectly at all times. Another reason is teachers’ responsibility for a curriculum, which can require creating expectations for students’ activities that sometimes conflict with students’ autonomy or makes them feel (temporarily) less than fully competent. Still another reason is students’ personal histories, ranging from divorce to poverty, which may create needs in some individuals which are beyond the power of teachers to remedy.

The result from students’ point of view is usually only a partial perception of self-determination, and therefore a simultaneous mix of intrinsic and extrinsic motivations. Self-determination theory recognizes this reality by suggesting that the “intrinsic-ness” of motivation is really a matter of degree, extending from highly extrinsic, through various mixtures of intrinsic and extrinsic, to highly intrinsic (Koestner & Losier, 2004). At the extrinsic end of the scale is learning that is regulated primarily by external rewards and constraints, whereas at the intrinsic end is learning regulated primarily by learners themselves. Table 6-3 summarizes and gives examples of the various levels and their effects on motivation. By assuming that motivation is often a mix of the intrinsic and extrinsic, the job of the teacher becomes more realistic; the job is not to expect purely intrinsic motivation from students all the time, but simply to arrange and encourage motivations that are as intrinsic as possible. To do this, the teacher needs to support students’ basic needs for autonomy, competence, and relatedness.

Using Self-Determination Theory in the Classroom
What are some teaching strategies for supporting students’ needs? Educational researchers have studied this question from a variety of directions, and their resulting recommendations converge and overlap in a number of ways. For convenience, the recommendations can be grouped according to the basic need that they address, beginning with the need for autonomy.

Supporting Autonomy in Learners
A major part of supporting autonomy is to give students choices wherever possible (Ryan & Lynch, 2003). The choices that encourage the greatest feelings of self-control, obviously, are ones that are about relatively major issues or that have relatively significant consequences for students, such as whom to choose as partners for a major group project. But choices also encourage some feeling of self-control even when they are about relatively minor issues, such as how to organize your desk or what kind of folder to use for storing your papers at school. It is important, furthermore, to offer choices to all students, including students needing explicit directions in order to work successfully; avoid reserving choices for only the best students or giving up offering choices altogether to students who fall behind or who need extra help. All students will feel more self-determined and therefore more motivated if they have choices of some sort.

Teachers can also support students’ autonomy more directly by minimizing external rewards (like grades) and comparisons among students’ performance, and by orienting and responding themselves to students’ expressed goals and interests. In teaching elementary students about climate change, for example, you can support autonomy by exploring which aspects of this topic have already come to students’ attention and aroused their concern. The point of the discussion would not be to find out “who knows the most” about this topic, but to build and enhance students’ intrinsic motivations as much as possible. In reality, of course, it may not be possible to succeed at this goal fully—some students may simply have no interest in the topic, for example, or you may be constrained by time or resources from individualizing certain activities fully. But any degree of attention to students’ individuality, as well as any degree of choice, will support students’ autonomy.

Supporting the Need for Competence
The most obvious way to make students feel competent is by selecting activities which are challenging but nonetheless achievable with reasonable effort and assistance (Elliott, McGregor, & Thrash, 2004). Although few teachers would disagree with this idea, there are times when it is hard to put into practice, such as when you first meet a class at the start of a school year and therefore are unfamiliar with their backgrounds and interests. But there are some strategies that are generally effective even if you are not yet in a position to know the students well. One is to emphasize activities that require active response from students. Sometimes this simply means selecting projects, experiments, discussions and the like that require students to do more than simply listen. Other times it means expecting active responses in all interactions with students, such as by asking questions that call for “divergent” (multiple or elaborated) answers. In a social studies class, for example, try asking “What are some ways we could find out more about our community?” instead of “Tell me the three best ways to find out about our community”. The first question invites more divergent, elaborate answers than the second.

Another generally effective way to support competence is to respond and give feedback as immediately as possible. Tests and term papers help subsequent learning more if returned, with comments, sooner rather than later. Discussions teach more if you include your own ideas in them, while still encouraging students’ input. Small group and independent activities are more effective if you provide a convenient way for students to consult authoritative sources for guidance when needed, whether the source is you personally, a teaching assistant, a specially selected reading, or even a computer program. In addition, you can sometimes devise tasks that create a feeling of competence because they have a “natural” solution or ending point. Assembling a jigsaw puzzle of the community, for example, has this quality, and so does creating a jigsaw puzzle of the community if the students need a greater challenge.

Supporting the Need to Relate To Others
The main way of supporting students’ need to relate to others is to arrange activities in which students work together in ways that are mutually supportive, that recognize students’ diversity, and minimize competition among individuals. We will have more to say about this strategy in Chapter 8 (“Instructional Strategies”), where we describe several varieties of cooperative learning, as well as some of their pitfalls to be avoided. For now, simply note that having students work together can happen in many ways. You can, for example, deliberately arrange projects that require a variety of talents; some educators call such activities “rich group work” (Cohen, 1994). In studying in small groups about medieval society, for example, one student can contribute his drawing skills, another can contribute his writing skills, and still another can contribute his dramatic skills. The result can be a multi-faceted presentation—written, visual, and oral. The groups needed for rich group work provide for students’ relationships with each other, whether they contain six individuals or only two.

And there are other ways to encourage relationships among students. In the jigsaw classroom (Aronson & Patnoe, 1997), for example, students work together in two phases. In the first phase, groups of “experts” work together to find information on a specialized topic. In a second phase the expert groups split up and reform into “generalist” groups containing one representative from each former expert group. In studying the animals of Africa, for example, each expert group might find information about a different particular category of animal or plant; one group might focus on mammal, another on bird, a third on reptiles, and so on. In the second phase of the jigsaw, the generalist groups would pool information from the experts to get a more well-rounded view of the topic. The generalist groups would each have an expert about mammals, for example, but also an expert about birds and about reptiles.

As a teacher, you can add to these organizational strategies by encouraging the development of your own relationships with class members. Your goal, as teacher, is to demonstrate caring and interest in your students not just as students, but as people. The goal also involves behaving as if good relationships between and among class members are not only possible, but ready to develop and perhaps even already developing. A simple tactic, for example, is to speak of “we” and “us” as much as possible, rather than speaking of “you students.” Another tactic is to present cooperative activities and assignments without apology, as if they are in the best interests not just of students of “us all” in the classroom, yourself included.

Keeping Self-Determination in Perspective
In certain ways self-determination theory provides a sensible way to think about students’ intrinsic motivation and therefore to think about how to get them to manage their own learning. A particular strength of the theory is that it recognizes degrees of self-determination, and bases many ideas on this reality. Most people recognize combinations of intrinsic and extrinsic motivation guiding particular activities in their own lives. We might enjoy teaching, for example, but also do this job partly to receive a paycheck. To its credit, self-determination theory also relies on a list of basic human needs—autonomy, competence, and relatedness—that relate comfortably with some of the larger purposes of education.

Although these are positive features for understanding and influencing students’ classroom motivation, some educators and psychologists nonetheless have lingering questions about the limitations of self-determination theory. One is whether providing merely choices actually improves students’ learning, or simply improves their satisfaction with learning. There is evidence supporting both possibilities (Flowerday & Schraw, 2003; Deci & Ryan, 2003), and it is likely that there are teachers whose classroom experience supports both possibilities as well. Another question is whether it is possible to overdo attention to students’ needs—and again there is evidence for both favoring and contradicting this possibility. Too many choices can actually make anyone (not just a student) frustrated and dissatisfied with a choice the person actually does make (Schwartz, 2004). Furthermore, differentiating activities to students’ competence levels may be impractical if students are functioning at extremely diverse levels within a single class, as sometimes happens. Differentiating may be inappropriate, too, if it slows holds a teacher back from covering key curriculum objectives which students need and which at least some students are able to learn. These are serious concerns, though in our opinion not serious enough to give up offering choices to students or to stop differentiating instruction altogether. In Chapter 7 (“Creating a Positive Learning Environment”) and Chapter 8 (“Instructional Strategies”), therefore, we explain the practical basis for this opinion, by describing workable ways for offering choices and recognizing students’ diversity.

(back to Chapter 6...)


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User talk:Etc

help requested
I have recently finished to write a book on m:b:en:Philosophy of Science in Russian wikibook Философия науки. I want to find somebody to translate it to English. Can you help me with this? P.S. I am interesting to write some books on math and computer science. On math I am currently working on m:b:ru:Знакомство с методом математической индукции and on computer science on Object oriented, m:b:en:Computer programming/Procedural programming and m:b:en:User:Alexsmail/Computer programming/How Objects should be correctly compared in Java (all this is on currently on hold). In my English texts I have a lot of grammar mistakes, so I need somebody to correct one. I want that all that I am writing will be on English. It can be translating of written on another language text or original text.

P.P.S. I have some material on math in Hebrew. Also hebrew wikibook has some material. It can be nice, while not mandatory, if you will know Hebrew too.

Я недавно закончил писать книгу в русском викиучебнике Философия науки. Я хотел бы найти кого-то ктобы перевёл бы его на английский m:b:en:Philosophy of Science. Не могли бы вы мне в этом помочь? P.S. Я хочу написать пару книг по математике и компьютерным наукам (программированию). По математике я начал работать над m:b:ru:Знакомство с методом математической индукции, а по компьютерным наукам над Object oriented, m:b:en:Computer programming/Procedural programming и m:b:en:User:Alexsmail/Computer programming/How Objects should be correctly compared in Java (пока я оставил это). Я пишу на английском со многими грамматическими ошибками, мне нужен кто-то, чтобы их исправлять. Я хочу, чтобы все мои книги были на английском. Это может быть как перевода с другого языка, так и оригинальный, изначально написанный на английском текст. P.P.S. По математике, у меня часть материала на иврите, да и в ивритском викиучебнике можно взять. Было бы прекрасно, если бы вы владели также ивритом. Но вовсе не обязательно. alexsmail 16:02, 26 August 2007 (UTC)

title: User talk:Etc


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User talk:Lakeshapickering

Come introduce yourself at the new users page. If you have any questions, you can ask there or contact me personally. Mattb112885 (talk to me) 16:13, 25 August 2007 (UTC)

title: User talk:Lakeshapickering


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Logic for Computer Science/Logics

=Sub-FO Logics=

Modal Logic
Modal logic expands propositional logic by operators for the modalities possibility and necessity. These basic modal operators are usually written $$\Box$$ (or L) for necessarily and $$\Diamond$$ (or M) for possibly. Each can be defined from the other in the following way:

 * $$\Diamond P \leftrightarrow \lnot\, \Box\, \lnot\, P.$$

Conjunctive Logic
Conjunctive Logic is a fragment of FO that is restricted to atomic FO expressions joined by conjunctions that can be preceded by existential quantifiers. It is especially important in Database theory.

Definition CON

 * 1) Atom
 * 2) $$\varphi \land \psi$$
 * 3) $$\exists_x \varphi$$

Remarks

 * 1) In other words: a CON-formula is a (relational) FO-formula built from atomic formulas using only conjunction and existential quantification.
 * 2) The semantics of FO applies here correspondingly.
 * 3) The 'usual' notions of free and bound variables also apply here.
 * 4) A formula of the form $$\exists_{x_1} ... \exists_{x_n} \varphi_1 \land ... \land \varphi_m$$, where each φ is quantifier free, is said to be in Normal Form
 * 5) Each CON formula is equivalent to one in Normal Form
 * 6) All CON formulas are satisfyable

Examples

 * 1) $$\exists_x (\varphi(x, y) \land \psi(x, y))$$ has a bound x and a free variable y
 * 2) $$\exists_x (\varphi(x) )\land \exists_y (\psi(y))$$ is equivalent to $$\exists_x \exists_y (\varphi(x) \land \psi(y))$$. The latter is said to be in normal form.

Equality

Additionally Equality between variables or constants can be be introduced by
 * $$x \equiv y$$

Example. Not always satisfiable. Each satisfiable CON formula is equivalent to one without equality.

=Higher-order Logics=

Fixed-Point Logics
Fixed-Point Logics augment the syntax of FO by a fixed-point operator, a mechanism that enables recursion on expressions, and so allows higher expressive power. This idea is quite similar to adding the construct of while-loop to an imperative programming language.

Example Transitive Closure

Consider the transitive closure of a graph G. For distance one we have:

$$G(x, y)\,$$

for distance up to two:

$$G(x, y) \lor \exists_z ( G(x, z) \land G(z, y) )$$

so we can go on by expanding this disjunction for further fixed distances (only). In order to express transitive closure for an arbitrary distance (what is vital for most situations) recursion can be introduced employing:

$$\varphi(T) = G(x, y) \lor T(x, y) \lor \exists_z ( T(x, z) \land G(z, y) )$$

where T is the transitive closure up to some i. Thus φ(T) gives the transitive closure up to i + 1. So it can be defined a sequence

$$J_0 = \empty ; J_i = \varphi(J_{i-1}), i > 0$$

that clearly gives the transitive closure for some k, i.e. the sequence converges (i.e. Jk = Jk+j, for all j > 0) and its limit is the transitive closure.

In the illustration we have an initial graph G as in (a) and thus

(a) as $$J_1 = G(x, y)\,$$

(b) as $$J_2 = G(x, y) \lor \exists_z ( G(x, z) \land G(z, y)$$

and the fixed point (c) as

$$J_3 = G(x, y) \lor \exists_z ( G(x, z) \land G(z, y) ) \lor \exists_z ( \exists_t ( G(x, t) \land G(t, z) ) \land G(z, y) )$$

and thus J3 = J4 = ... .

♣

As we have seen in this example, recursion can be used to express formulas of arbitrary length. But since we are always dealing with finite formulas here some terminator must be given for the recursion. This role can be played by the fixpoint. In the above example such a fixpoint exists. But this is not always the case, as we see next.

Example

TODO Jumper

♣

As we have seen in this example, a fixpoint of a recursion not always exists. So we must be careful defining a recursion-based logic. We extend FO by a fixpoint operator to PFP for cases where a fixpoint exists.

Partial Fixed-Point Logics (PFP)
TODO

♣

The above assumption that a fixpoint exists it not really satisfying, so one now can think of restrictions on the recursion in order to enforce the existence in every case. Therefore three ideas are introduced: monotonicity, positiveness and inflation of the recursion.

Inflationary Fixed-Point Logics (IFP)
Notion

TODO Life-Game

Definition

TODO

Least Fixed-Point Logics (LFP)
Notion

TODO

Definition

TODO

♣

Comparison of IFP and LFP
TODO

♣

=Characteristics of FO=

title: Logic for Computer Science/Logics