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Talk:Meteor Crater

Discussion without Headers
Wouldn't this article be better located at Meteor Crater as the most common name, per the Naming conventions?

Consider google's results.
 * "Barringer Crater": 5,330
 * "Meteor Crater": 56,900

Now, some references to "meteor crater" may be generic, but even if we include the location:
 * "Meteor Crater" and Arizona: 36,400

So clearly, "Meteor Crater" is many times more popular, and I think Barringer Crater should be the redirect. What do you think?--Pharos 02:02, 21 Nov 2004 (UTC)

Note: According to the United States Geological Website, and the Bureau of Geographica; Nomenclature page found at the USGS website, the offical name for the Crater has been since 1946, "METEOR CRATER" not Barringer Crater. It has never been officially named Barringer Crater, since it recieved its name of Meteor Crater, back in 1907 when Herman L. Fairchild a geologist at the University of Rochester, New York gave it that name. HIs reasoning was simple. If we name meteorites after the nearest Post Office or a geographical feature, than why not name craters using the same convention, and he proceeded to do just that. It was picked upo a year later by George Perkins Merrill of the United States National Museum, today part of the Smithsonian complex, where he also used the name Meteor Crater. It was made officialin 1946 by the Bureau of Geographical Nomenclature. — Preceding unsigned comment added by 67.173.46.108 (talk • contribs) 19:20, 9 August 2012

 * Hmmm, I'm not sure, for two reasons:
 * 1) "Barringer Crater" is the crater's official name, and I'm not sure if the naming conventions refer specifically to the proper names of locations. It's true, however, that were this a person's name we'd go by the most common reference.
 * But 2) I'd be worried about making this the main site of an article entitled "Meteor crater." According to Naming_conventions, we shouldn't "write or put an article on a page with an ambiguously-named title as though that title had no other meanings." For the moment there is no article on "meteor crater," but clearly this is not only the name of a specific site, but also a general term for a hole in the ground caused by a crater. By putting this article in the one with the more general term, we'd be effectively blocking out that page, and preventing the creation of a more general article.

 * I'd go for the specificity argument over the common name one personally, though I can also see reasons for changing the title. -- Asbestos 17:45, 21 Nov 2004 (UTC)

 * I'm undecided on this. Prior to this article, I had only heard this crater referred to as Meteor Crater, never as Barringer Crater. However, I'm just an amateur; I have no formal education in geology or astronomy. Meteor Crater is a well-established name for this crater, though. Furthermore, I do not think that Meteor Crater could be used as a generic name, as it is technically a misnomer—any crater produced in such a manner should be called a meteorite crater. So I don't think we have to worry about; however, for the same reason, Barringer Crater probably is a better name.—Knowledge Seeker দ (talk) 01:24, 5 Feb 2005 (UTC)

If "Meteor Crater" is so ambiguous and vague, then how is it that in an encyclopedia of a half-million articles, it seems to work perfectly fine as a redirect to "Barringer Crater"? When something is a redir instead of a disambig page, that's a pretty strong hint that nobody is confused about where the redirecting name should go. "Meteor Crater" will be perfectly fine as a name - "Barringer Crater" is OK, but a little on the pedantic side. Stan 05:43, 5 Feb 2005 (UTC)

 * "Meteor Crater", capitalized, refers to this specific impact crater. Only "meteor crater", uncapitalized, is generic and the (quite rightly) redirects to impact crater. As to "formal names", Wikipedia, is not intended primarily for professional astronomers etc. but for the lay reader, who is much more likely to be familiar with "Meteor Crater".--Pharos 1 July 2005 22:51 (UTC)

I was very confused when I came across this article and saw that it was called "meteor crater." Shouldn't it be called by its actual name? 129.2.167.206 (talk) 18:28, 19 December 2009 (UTC)
 * Already at the time the above enquiry was posted, the origin of the name was explained in the introduction section of the article, in the second sentence of the first paragraph, so the user was obviously inattentive. There's only so much we can do to serve the reader; I don't see how the information could be made more prominent for the convenience of the reader. --Florian Blaschke (talk) 09:33, 13 May 2013 (UTC)

This issue has resurfaced recently, with a user attempting to insert "Barringer Crater" into many areas of the article. I agree that it is in popular use, but it is clearly secondary and should be addressed as such. There are currently 7,700 Google Scholar references to "Meteor Crater" and 1,600 references to "Barringer Crater." "Meteor Crater" is also a searchable term in Google's Ngram viewer, while "Barringer Crater" is not a valid search term due to insufficient use. -- meteoritekid 18 March 2023 21:53 (UTC)

Indigenous Name?
What did the first Americans call the Meteor Crater? Two different guides at the Visitor's Center told me they didn't have a name for it, but that's just not possible.--Hugh7 (talk) 05:52, 30 November 2015 (UTC)

New Nature Article
Someone who knows a lot about physics and/or the crater should go through and make sure that all the information is correct in light of the new analysis from Nature. Dave 00:10, Mar 14, 2005 (UTC)

Use of definite article
Hi Pharos—you wanted the article to start with "Barringer Crater is a famous impact crater..." instead of "The Barringer Crater is a famous impact crater...", and suggested I look at other crater names. A brief glance at the articles on famous craters finds that most of them start the way I suggested: Indeed, this is a style employed when talking about the majority of geological formations: ...and so on so forth.
 * "The Manson impact crater is located..."
 * "The Chesapeake Bay impact crater was formed by..."
 * "The Haughton impact crater is located..."
 * "The Sudbury Basin is the second largest impact crater..."
 * "The Silverpit crater is located..."
 * "The Rio Cuarto craters are..."
 * "The Weaubleau-Osceola structure is thought..."
 * "The Nördlinger Ries is a depression..."
 * "The Catskill Mountains are not..."
 * "The Rocky Mountains are a..."
 * "The Grand Canyon is a colorful..."
 * "The Amazon River of South America is..."

Also note that the Barringer Crater website, http://www.barringercrater.com/science/ starts their article with "The Barringer Meteorite Crater is a gigantic hole...". The point isn't whether its name is "Barringer Crater" or "The Barringer Crater", obviously it's the former, but when discussing the Crater and starting an article on it, as in the case of the hundreds of articles on similar subjects in this project, you generally start with "The Barringer Crater".—Asbestos | Talk  13:51, 21 July 2005 (UTC)

 * I have taught SAT and TOEFL for 6 years. There is no difference between "The Barringer Crater..." and "Barringer Crater..." except that "the" can emphasize the uniqueness of the proper noun, e.g. "The Empire State Building..." is standard usage probably b/c nobody ever calls it "Empire State Building." Generally speaking, if an article is called for, you must use "the" in this case (unique proper noun). Dudeman1st (talk) 17:50, 21 December 2007 (UTC)

Size of meteorite, explosive power, and debris from impact
After reading about Ivy Mike, I'm a little confused why a 10.4 megaton explosion would eject 80,000,000 tons of soil while this much smaller explosion (2.5 megatons according to the article) "dug out 175 million tons of rock."

Also the size of the explosion seems like it might be off. The crater left by Ivy Mike is 1.6km in diameter and 50m deep; and similarly Tswaing crater is [1km in diameter, 100m deep], and also [estimated at 10 megatons]. Proportionally speaking, shouldn't Barringer Crater also register in the ballpark of 10 megatons? I'm having a hard time believing it was only 2.5 megatons with a radius of 1.2km's and a depth of 170m.

Tswaing Crater: 1.1km 100m ~10megatons Ivy mike: 1.6km 50m 10.2megatons Meteor Crater: 1,200m 170m 2.5-6.5 megaton

The math currently works out to about 4 megatons for Meteor crater, because the Nature team downed the velocity from 16 km/s to 12.8 km/s and severely reduced the size of the meteorite.

IE/

For a roughly spherical object: 4/3 * pi * Density * Radius^3 = Mass

So, 4/3 * pi * 3 {tonnes / m^3} * 25{m}^3 = 196,349 tonnes

Kinetic Energy = (Mass * Velocity^2)/2

So, (196,349 {tonnes} * 12,800 {m/sec}^2) / 2 = 1.608 * 10^13 {tonnes*(m/sec)^2} or 10^13 joules.

and since, 1 kilogram of TNT releases 10^8/25 = 4 * 10^6 Joules of energy

(1.608 * 10^13 joules) / (4 * 10^6 joules) = ~4 megatons

I just find this to be terribly suspect, since we have real world data of what a 10.2 megaton explosion does and the two look virtually the same. Xtraeme 11:05, 30 May 2007 (UTC)

 * I can’t comment on the actual numbers, but Ivy Mike was detonated at surface so most of the energy was dissipated into the atmosphere. In contrast, impact craters are produced by projectiles that penetrate some depth (variable depending on angle of impact, velocity, density, strength of projectile and target) into the earth before exploding, so almost all of the energy is deposited into the earth and therefore should produce a deeper crater with more ejecta for the same energy. The best comparison would be between underground nuclear tests and impact craters of similar energy. With impact craters, the target properties are also quite important. For example I’d expect the same energy yield to produce a smaller crater in the Tswaing area (strong granite) compared to the Barringer/Meteor crater (weaker sedimentary rocks). --Zamphuor 12:25, 30 May 2007 (UTC)

 * The above calc seems to use a density of 3 tonnes/m^3, but for an iron-nickel meteorite shouldn't that be nearer 8 tonnes/m^3 (thus upping the mass and energy) ? - Rod57 (talk) 07:32, 30 May 2011 (UTC)

Hey all,

Can someone explain the figure (quote) "half of the impactor's 300,000 tonnes (330,000 short tons) bulk" when Canyon Diablo (meteorite) tells a Total Known Weight (TKW) of 30 tons ? Is this a kind of typoo ?? --rosetta 17:40, 16 June 2009 (GMT) —Preceding unsigned comment added by 78.48.71.22 (talk)

The sentence means that half of the impactor's mass was vaporized and dispersed during atmospheric passage, before hitting the ground. Most of what was left was vaporized by a shockwave that was transmitted into the impactor from the point of impact, immediately after contact with the ground. Canyon Diablo meteorites are the leftovers of the impactor that either separated from the main mass in flight and aerobraked to a lower velocity or sheared off the back end before the rarefaction wave got there.

As for a couple of other points, I don't know any modern source that claims any significant portion of the impactor's mass is hidden under crater wall and it doesn't fit my understanding of physics. We've known since Barringer's day that there is no large magnetic anomaly in the structure. I also don't know how much weight should be given the Nature paper, given that everyone has been saying 10 MT all along. One "breakthrough" paper like Science and Nature tend to publish isn't exactly a definitive source. Results must be confirmed by further work before we re-write the body of literature on how the crater formed, and their number looks like an outlier to me. I say if we can find three or more sources that cite 10 megatons, we throw the Nature paper out. Geogene (talk) 23:27, 19 June 2009 (UTC)

Excuse the ignorance and probably a stupid question, but when you say that the meteorite was 50 meters across, are you referring to the dimension in space or the dimension at time of impact? Would appreciate a clarification in the article. Olan7allen (talk) 19:40, 9 August 2009 (UTC)

 * Nobody knows; explosive power is pretty easy to estimate, but velocity and mass vary with different sources. Here's a university article claiming that the asteroid in space had a diameter of 30 meters or larger. Geogene (talk) 16:15, 13 August 2009 (UTC)

Most likely the impactor was lot larger then what it was initially suggested. Even if the impactor was highly dense, nickel/iron impactor, it would be at least 60m weighing over 1.4 million tons. It would leave impact creator roughly 1.2km in diameter. However, if it was a standard rock/ice composition, then impactor was nearly 100m across (90x60x50m) weighing roughly 1.1 million tons. Impactor in both cases would impact at realistic speed of ~40 000kmph. — Preceding unsigned comment added by 195.26.122.240 (talk) 16:29, 9 January 2024 (UTC)

Images
Let's not overdo the number of images - four images, one per section, is quite enough! Also, please consider what value the images actually bring to the article. -- ChrisO 09:26, 2 October 2005 (UTC)
 * Two of the image captions say that the mass of the meteorite is buried under the crater, while the article says that nearly all of it was vaporized on impact. Another image is captioned "Meteor crater", as if it were some other crater than the Barringer Crater. These captions need work.—Wdfarmer (talk) 01:14, 30 June 2011 (UTC)

Cites needed
For a subject with so much published research on it, this page is woefully under-cited. If you are the one with access to these materials, please cite at least once per paragraph. The date of human inhabitation is unnecessary and both highly speculative and controversial. Dudeman1st (talk) 18:05, 21 December 2007 (UTC)

Topographic map
Hello,

Where can I find a very precise topographic map of the Barringer Crater ?

Thank you ! —Preceding unsigned comment added by 91.176.37.125 (talk) 16:58, 31 December 2007 (UTC)

I recall that there is a very detailed map of the crater itself on display in the visitor center, maybe you can get a copy there —Preceding unsigned comment added by 88.117.115.181 (talk) 23:01, 6 January 2008 (UTC)

And here: —Preceding unsigned comment added by Mmairing (talk • contribs) 23:48, 6 January 2008 (UTC)

Citing the museum at the visitor's center
If someone were willing to actually visit the Meteor Crater (which I did about a month ago, before looking at this article), a source of good citations would be the museum itself at the Visitor's Center.

Also, at the museum there is a display that challenges the assertion in this article that "Very little of the meteorite remained within the pit that it had excavated." The display shows a significant chunk of the meteorite buried about as far underground as the diameter of the crater, along an angled path from the center of the crater that indicates the angle of the original impact. --Mosher (talk) 16:14, 31 January 2008 (UTC)

The (privately owned) visitor center contains a number of dated exhibits and is not a great reference. The museum has a specimen of Sikhote Alin on display, labelled as a hexahedrite (Sikhote Alin is a coarsest octahedrite), and older displays of the crater appear to take heavily from the museum's old educational material like this brochure, which date to the 1950s or earlier. It's a great place to take kids and to get the gist of what's going on at Meteor Crater, but it's not an authority on modern or completely accurate information. --Meteoritekid

Mileage from Flagstaff
BTW, the article was incorrect in stating that the BM Crater is located "35 miles" from Flagstaff. I was just there 6 days ago and drove there directly to and from Flagstaff. The distance is 58 miles. A simple check of Google Maps will confirm that. Ronstock (talk) 19:14, 24 April 2008 (UTC)
 * Please check your google maps again. You're way off. Americasroof (talk) 04:54, 19 September 2008 (UTC)

Why is it not round?
What caused the square-with-rounded-corners shape of this crater? Other craters are more or less round (circular). And indeed if a lot of energy is released at one point without any explicit directional guidance, one would expect its effects to be non-directional, i.e. equal in all directions, thus producing a circular crater. If the meteor impacted at an angle, I could see how the crater might be elliptical, but this one has a definite square shape. Any explanation? Rennybosch (talk) 02:51, 9 February 2008 (UTC)

 * Erosion? it is quite big, and subject for lot of tourist attention, so one would think it could be caused by that. any other ideas? —Preceding unsigned comment added by 213.115.44.58 (talk) 11:53, 6 December 2009 (UTC)

 * The crater was originally hemispherical but the walls of the crater have slumped over time. The floor you see today is actually a mass of rubble some 300m deep covering the "true" floor of the crater. -- ChrisO (talk) 12:02, 6 December 2009 (UTC)

 * A sentence (with ref) explaining this was added to the article in May 2009. The non-circular shape is attributed to pre-existing large-scale faulting at the impact site. Although the explosive force was equal in all directions, the rock strata were not equally strong in all directions, thus a non-circular crater was the result. Piperh (talk) 08:36, 18 July 2010 (UTC)

Inability to climb out in a C150
This seems interesting. If the prevailing wind is from one direction, they may have been trying to climb out the wrong side. If the wind from all directions went toward the center, it had to go somewhere and they should have been able to spiral climb in the center of the crater and escape. Not that pilots don't always think of things like that. The C150 with two people has an abysmal climb rate, of course. The wording of the last sentence could be improved - they didn't continue to fly in the same aircraft while pointing out the wreckage to visitors. 199.125.109.123 (talk) 20:07, 18 February 2008 (UTC)

 * A ref has been added to a somewhat detailed accident report for this crash. Apparently the plane did not run out of fuel (in fact, it caught fire upon crashing) nor is there explicit mention of downdrafts. My understanding (as a layman, not a licensed pilot) of spiral flight is that the rate of climb will be less than in straight-and-level flight because the lift vector of the wings is no longer vertical. There would be a limit to how tight a spiral can be flown before rate of climb would become negative. A high bank angle combined with low air speed needed for a tight spiral is an invitation to aerodynamic stall -- which is what happened in this case. Piperh (talk) 09:12, 18 July 2010 (UTC)

The official accident report http://www.ntsb.gov/ntsb/brief.asp?ev_id=79450&key=0 that's referenced in the Cessna 150 says nothing about downdrafts or the plan being trapped. It only says that the plane stalled during a 'low pass'.

Age conflict
This article says 50,000 years old, while the Canyon Diablo (meteorite) article says 20-40,000. Which is right?

Barringer Crater Mining Company
The article reads: "He persisted nonetheless and sought to bolster his theory by uncovering the remains of the meteorite"

Just to be clear, Barringer "persisted" and "sought" to make a great deal of money mining iron and platinum group elements from the remains of the meteorite. That was the purpose of his explorations there, it was what he told his investors they were doing, and it's why and how he filed a mineral claim on the crater, which was on Federal land.

There's nothing wrong with smart people making a good living. And Barringer was a very sharp man. But it isn't like he was drilling on an NSF grant or something. —Preceding unsigned comment added by Geogene (talk • contribs) 16:53, 10 June 2009 (UTC)

Add Crater Infobox?
Someone may want to apply crater template

--YakbutterT (talk) 23:23, 18 February 2010 (UTC)

Should coon mountain be mentioned in the article
It seems this crater was known as coon mountain, and is cited as such in some literature. Indeed, the redirect seems to point here, but shouldn't it be mentioned in the article as well? HrundiEuphorion (talk) 21:54, 2 September 2010 (UTC)

Holy Moly
You guys got good pictures! Good job!KF5LLG (talk) 12:23, 2 December 2011 (UTC)

File:Meteor Crater - Arizona.jpg to appear as POTD soon
Hello! This is a note to let the editors of this article know that File:Meteor Crater - Arizona.jpg will be appearing as picture of the day on April 18, 2012. You can view and edit the POTD blurb at Template:POTD/2012-04-18. If this article needs any attention or maintenance, it would be preferable if that could be done before its appearance on the Main Page so Wikipedia doesn't look bad. :) Thanks! — howcheng  {chat} 17:33, 16 April 2012 (UTC)

More work needed!
What was the actual effect of the strike? So far all this article states is a massive crater was formed by a huge explosion. And? What was the blast radius? Did the strike change global weather conditions? Need more to be done. — Preceding unsigned comment added by 109.145.118.197 (talk) 12:28, 18 April 2012 (UTC)
 * Er, there's really not much known about those effects, because they don't leave lasting evidence. We can speculate, based on the size of the crater and the approximate period it happened in, but that's not terribly helpful in the long run.— The Hand That Feeds You :Bite 15:45, 18 April 2012 (UTC)

The article needs info on the radius of the ejecta blanket. According to the museum, the radius was 1 mile, but I don't have any citations. Light Peak (talk) 23:02, 19 February 2013 (UTC)

Total Known Mass / weight of meteor
Back in 2009 a contributor to this Talk page ('rosetta' 17:40, 16 June 2009 (GMT)) asked if the 300,000 tonnes cited as the mass of the meteorite was not possibly a "typo." Many references cite a weight / mass of "30 metric tons" (see www.lpi.usra.edu/meteor/... and meteorites.wustl.edu/ as well as the Wikipedia article "Canyon Diablo (meteorite)") for the pre-impact meteor / meteorite. The poster, 'rosetta' never received a relevant response to this question / concern so I thought I'd bring it up again here. This is not my area of expertise but, since there does seem to be some disagreement / some ambiguity, I thought it might be 'safer' to remove the explicit reference to 300,000 tonnes for now since it is not needed to make the point about 1/2 of the meteorite's bulk being vaporized during its descent.
 * "...It is believed that about half of the impactor's 300,000 metric tons (330,000 short tons) bulk was vaporized during its descent, before it hit the ground...."

I hope more knowledgeable editors can find an appropriate reference / citation to add to the article if the mass is to be re-instated. Pugetbill (talk) 17:25, 18 April 2012 (UTC)

Diablo Canyon crater?
I'm aware that the meteorite is called "Diablo Canyon", but I can find no authority that the crater was ever so-called. GNIS gives eight variant names, but Diablo Canyon isn't one (Meteor Crater Detail at GNIS).

Also, I can find no support for JP Barringer's (ref 2) statement that natural features are named after the nearest post office. The GNIS policy says no such thing (US BGN Principles, Policies, and Procedures). If it was ever true, I don't know (though I doubt it considering the purpose of the BGN); however, is JP Barringer a reliable authority for this information? The source is merely a transcription of a speech he gave, so a primary source for all intents and purposes.Richigi (talk) 15:52, 20 November 2012 (UTC)

Former or formal
Is the name "Canyon Diablo Crater" a former (previous) or formal (official) name? DHN (talk) 18:39, 13 February 2013 (UTC)
 * Surely it is the former, or previous, name? David J Johnson (talk) 18:45, 13 February 2013 (UTC)
 * According to GNIS, it is neither formally nor formerly called Diablo. I requested a citation for the claim back in November; still haven't seen one. Richigi (talk) 22:17, 13 February 2013 (UTC)
 * Talking two different things here, the change I reverted was in the caption to the NASA image File:Landsat Meteor Crater.jpg which now states ...Diablo Canyon for which the meteorite is formerly named . The Canyon Diablo (meteorite) The ref there states: This is an OFFICIAL meteorite name. this reference. It is the name of the meteorite, not the name of the crater. Vsmith (talk) 11:17, 14 February 2013 (UTC)
 * Vsmith is right, the meteorite is named for Diablo Canyon, currently not formerly. The caption is about the meteorite. I just removed the adjective altogether since a qualifier isn't really necessary. Richigi (talk) 17:45, 14 February 2013 (UTC)

Map shows location incorrectly in Coconino County
The current infobox map shows the location as being in Coconino County, when it should be in Navajo County. Could someone who knows how to adjust these maps please correct that? Backspace (talk) 09:47, 18 March 2013 (UTC)
 * The crater is in Coconino County per USGS Flagstaff 30x60 quad. Winslow, about 25 km to the east, is just east of the county line in Navajo County. Vsmith (talk) 13:19, 18 March 2013 (UTC)
 * I just recently edited the article to reflect the point that it is located in Coconino County, but then immediately undid my edit because of a lot of conflicting evidence. All three relevant categories in the article said/say that it is in Navajo County, when I could see by the map (assuming that it was correct) that it was in Coconino County. I have actually been there, and at the time believed it to be in Coconino County, which is the primary reason that I did the original edit. Based upon your assessment I shall have to redo my undo. This will happen forthwith. Backspace (talk) 20:54, 18 March 2013 (UTC)
 * Good catch, I hadn't noticed the erroneous categories. Vsmith (talk) 22:54, 18 March 2013 (UTC)

The "Basket" Meteorite
The “Basket meteorite” that is mentioned in Revision as of 13:44, June 16, 2013 is for real. It is likely not notable enough to be included in this article. However people interested in what the “Basket meteorite” is and how it relates to Meteor Crater can go to and read either Long-lost meteorite comes home to Ariz. by John Faherty, The Arizona Republic, March 24, 2009 or page 7 of Starscan, Johnson Space Center Astronomical Society, Volume 25, Number 4 April 2009 Paul H. (talk) 01:42, 17 June 2013 (UTC)

Not the largest in the US?!
The Chesapeake bay crater article mentions that it is the largest impact crater in the US. Yet this article also claims Meteor Crater to be, and refers to a dubious (no measurements listed, nor a comparison) webpage mentioning this fact. However, the size of the two impact craters is so drastically different that it's obvious that the Chesapeake bay crater is the largest in the US, and this article is wrong to claim so. See http://en.wikipedia.org/wiki/Chesapeake_Bay_impact_crater — Preceding unsigned comment added by 75.92.167.159 (talk) 20:44, 30 August 2013 (UTC)

What about the evidence of electrical discharge event?
Geologist George P. Merrill found in 1908 that the rock layers underneath the crater are undisturbed, which does not fit the standard bolide impact model.

An electrical explanation of the crater envisions an approaching bolide entering the strongest region of Earth’s electric field and, under prodigious internal electrical stresses, beginning to discharge explosively and to fragment. Before reaching the surface it is likely to have already blown apart, for the same reason that comets have exploded millions of miles from the Sun and the Tunguska bolide exploded high in the earth’s atmosphere.

The apparent "reverse" stratification of the debris distributed by the event fits an electrical discharge model. A rotating, crater-producing electric arc will work down from the surface through layers of soil, spraying the material across a wide region. This could mean that the debris field would be laid down roughly in layers that reversed the strata of the surrounding terrain. Barringer himself found that “different types of rocks in the rim and on the surrounding plain appeared to have been deposited in the opposite order from their order in the underlying rock beds.” — Preceding unsigned comment added by Mattsileo (talk • contribs) 12:20, 7 August 2015 (UTC)
 * You're forgetting the high concentration of meteoritic material in the Crater's ejecta field. Citing Merrill from 1908 doesn't necessarily mean the strata really are undisturbed. Geologic survey techniques have gotten more sophisticated in the past 108-years. Why not search out considerably more recent findings using seismic wave mechanics to accurately image the layers? — Preceding unsigned comment added by 24.223.130.32 (talk) 01:15, 11 March 2016 (UTC)

What is the smaller crater-like circular feature to the south of Meteor Crater?
If you take a look just under 1 mile south of Meteor Crater, there is a much smaller circular feature that looks very much like an impact crater. Does anyone know what this feature is?

You can see it here: https://www.google.co.uk/maps/place/Meteor+Crater/@35.016979,-111.0262765,2399m/data=!3m1!1e3!4m5!3m4!1s0x872e745d7f38512f:0xe0c334a29e78fd9e!8m2!3d35.0275441!4d-111.0221236?hl=en

Markrlondon (talk) 23:45, 26 July 2016 (UTC)

— Preceding unsigned comment added by 24.223.130.32 (talk) 23:03, 26 September 2016 (UTC)

 * My guess is that it's another meteorite crater, from a piece broken off the larger meteor before impact.

"Formation" section; an issue of correct grammar
The meteorite was mostly vaporized upon impact, leaving few remains in the crater.

Is correct.

The meteorite was mostly vaporized upon impact, leaving little remains in the crater.

Is not.

"Little remains" means small pieces of meteorite; whilst probably literally true, this is not the meaning of the sentence.

78.149.209.252 (talk) 17:55, 14 July 2017 (UTC)

 * You were told by another editor, of long standing experience, that in modern usage both words were correct. I cannot see why you have brought this up again - unless you thought that we have forgotten about your previous "edit". Perhaps it is time for you to create an account, rather than hiding behind a IP number? David J Johnson (talk) 18:43, 14 July 2017 (UTC)

 * Yes indeed, on another users talk page - the points made were fairly absurd I thought; could you point out any Wikipedia guidelines that say incorrect grammar should be used?
 * Not sure what the purpose behind your aggressive tone is. 78.149.209.252 (talk) 23:32, 19 July 2017 (UTC)

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effects of collision
While the section was added in good faith, and so I'm reluctant to revert it without discussing it first, it has some significant problems. Chief among these are the lack of any supporting citations and the sense that it violates WP:OR. I'll remove the section if these problems aren't addressed promptly. --Kent G. Budge (talk) 23:12, 5 February 2020 (UTC)

Removed as unsourced speculation. Vsmith (talk) 23:26, 5 February 2020 (UTC)

A Commons file used on this page or its Wikidata item has been nominated for deletion
The following Wikimedia Commons file used on this page or its Wikidata item has been nominated for deletion: Participate in the deletion discussion at the. —Community Tech bot (talk) 19:25, 18 March 2023 (UTC)
 * American Meteorite Museum postcard, mid-to-late 1940s.jpg

title: Talk:Meteor Crater


text:
User:Vystrix Nexoth

Articles majorly contributed to

 * ROM hacking (created)

Supplementary pages

 * A formatted transcript of the Wikimedia Board of Trustees Debate from June 2007.
 * Images I have uploaded

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

title: User:Vystrix Nexoth


text: Category:Models by nationality

title: Category:Models by nationality


text:
Santa Sangre

Santa Sangre (Holy Blood) is a 1989 avant-garde surrealistic psychological horror film directed by Alejandro Jodorowsky and written by Jodorowsky along with Claudio Argento and Roberto Leoni. It stars Axel Jodorowsky, Adán Jodorowsky, Teo Jodorowsky, Blanca Guerra, Thelma Tixou, and Guy Stockwell. An international co-production of Mexico and Italy, the film is set in Mexico, and tells the story of Fenix, a boy who grew up in a circus and his struggle with childhood trauma. It is signed on Empire magazine's 2008 list of the 500 Greatest Movies of All Time.

Plot
The film starts with a naked figure sitting in a tree in a mental asylum. Nurses come out to him, to try to coax him off of his perch, using a plate of raw fish to persuade him to come down. As the nurses get him to put on some overalls, it is shown that he has a tattoo of a phoenix on his chest.

Years ago, Fenix spends his time performing as a "child magician" in a circus run by his father Orgo, the knife-thrower, and his mother Concha, a trapeze artist and aerialist. The circus crew also includes, among others, a tattooed woman, who acts as the object of Orgo's knife-throwing feats, her adopted daughter Alma (a deaf mute mime and tightrope walker whom Fenix is close to), Fenix's dwarf friend Aladin, a pack of clowns and an elephant. Orgo carries on a very public flirtation with the tattooed woman, and their knife-throwing act is heavily sexualized.

Concha is also the leader of a religious cult that considers as its patron saint a girl who was raped and had her arms cut off by two brothers. Their church is about to be bulldozed at the behest of the landowner, and the followers make one last stand against the police and the bulldozers. A Roman Catholic Monsignor arrives to attempt to resolve the conflict, but after he enters the temple to inspect it he deems it sacrilege and angrily leaves in disgust, so the demolition is carried out. Fenix leads Concha back to the circus, where she discovers Orgo's affair, but Orgo, being also a hypnotist, puts Concha in a trance and rapes her.

The circus elephant dies, much to Fenix's grief, and a public funeral is conducted, in which the elephant is paraded through the city inside a giant casket. The casket is then dropped into the city dump, where scavengers open it up and proceed to carve up the elephant and take away the meat. Orgo chides Fenix for crying "like a little girl" and tattoos a spread-eagled phoenix onto his chest, identical to the one on his own chest, using a knife dipped in red ink. This tattoo, Orgo says, will make Fenix a man.

Later on, Concha, during her trapeze act, sees Orgo and the tattooed woman sneak out of the big top. She chases after them and, seeing them sexually engaged, pours a bottle of sulphuric acid onto Orgo's genitals. Orgo retaliates by cutting off both her arms (much like the girl previously venerated). He then walks into the street and slits his own throat. Fenix witnesses this, locked inside a trailer. He then sees the tattooed woman drive off with Alma.

Back in the present, Fenix is taken on a trip out of the asylum to a movie theater along with other patients, most of whom have Down syndrome. A pimp intercepts them and persuades them to take cocaine and follow him to meet an overweight prostitute. Fenix then spots the tattooed woman, who is now a prostitute, and becomes consumed with rage. Back in the asylum, Fenix's armless mother Concha calls out for him from the street and he escapes by climbing down a rope from his cell window. The tattooed woman is shown trying to prostitute Alma, who runs away and sleeps on the roof of a truck. The tattooed woman is then killed by the hands of an unseen assailant.

Fenix and Concha go on to perform an act whereby he stands behind her and moves his arms so that they appear to be Concha's arms. But Concha soon starts to use her son's hands to kill women whom Fenix is interested in, including a young performer and a cross-dressing wrestler. A dream sequence subsequently shows that Fenix has killed many more women, all of whom haunt him.

Alma finds Fenix and together they plan to run away from Concha. She tries to force Fenix to murder Alma as well, but, after a struggle, he manages to plunge a knife into Concha's stomach. She vanishes, but not before taunting Fenix by saying she will always be inside of him. Through a quick series of flashbacks, it is revealed that Concha in fact died after being maimed by Orgo, and that Fenix has kept a mannequin of his armless mother for performing on stage and at home, which also now appears in reality to be a thoroughly dilapidated house. He destroys the home-made temple and throws away the mannequin with the help of his imaginary childhood friends, Aladin and the clowns.

Alma proceeds to lead Fenix outside the house where police are waiting and order them to put up their hands. As they both comply, Fenix watches his own hands in awe as he does so. Fenix's realization that he has finally regained control of his hands brings him joy and peace.

Development
Roberto Leoni, who had worked in the library of a psychiatric hospital where he had been in contact with people suffering from mental disorders, developed a story about dissociative identity disorder that he told Claudio Argento during a time they worked together. Argento appreciated the story and added to it, and with Leoni, they decided to present it to the director who seemed to them the most suited to the material, Alejandro Jodorowsky. After his cult film The Holy Mountain of 1974, Jodorowsky was asked to direct a film version of Frank Herbert’s epic 1965 science fiction novel Dune but the project had collapsed, and except for the children’s fable Tusk in 1980 he had stopped directing films, working as a comics writer in France.

Jodorowsky developed this story, also telling Leoni the story of Gregorio Cárdenas Hernández, which were in some respects similar, and together they wrote the script of Santa Sangre.

Writing
Roberto Leoni stated that an episode with a patient in the psychiatric hospital was probably the origin of Santa Sangre because over time he conceived "a story in which even the worst demon actually can't forget he is an angel." In fact, Fenix the character that Leoni created together with Jodorowsky is a serial killer, but "…every time he kills you feel sorry for him, that is you are sorry more for him than for the victim."

Release
Though a Mexican and Italian co-production, Santa Sangre is in English. In the United States, it was primarily rated NC-17 for "several scenes of extremely explicit violence". An edited version was released with an R rating for "bizarre, graphic violence and sensuality, and for drug content". Regardless, Santa Sangre did not receive a wide release in the U.S., only screening at a few theaters familiar with Jodorowsky's previous work.

In 2004 Anchor Bay released a DVD in the UK. On 25 January 2011, Severin Films gave the film a release on both DVD and Blu-ray with more than "five hours of exclusive extras". On Halloween 2019, Morbido Fest, a Mexico City-based festival, held a celebratory 30th anniversary screening of Santa Sangre remastered in 4K by Severin Films from a scan of the original camera negative. In Italy, from 25 to 27 November 2019, the Videa film society celebrated the 30th anniversary by screening the 4K restored version at select theatres.

Critical response
The film generally was critically well received, eventually being ranked 476th on Empire's 2008 list of the 500 greatest movies of all time. A reviewer from the British Film 4 describing the film as "one of Jodorowsky's finest films" which "resonates with all the disturbing power of a clammy nightmare filtered through the hallucinatory lens of 1960s psychedelia."

Roger Ebert said that he believed it carried the moral message of genuinely opposing evil, rather than celebrating it like most contemporary horror films. Ebert described it as "a horror film, one of the greatest, and after waiting patiently through countless Dead Teenager Movies, I am reminded by Alejandro Jodorowsky that true psychic horror is possible on the screen – horror, poetry, surrealism, psychological pain, and wicked humor, all at once."

, the film had an 86% rating on review aggregator website Rotten Tomatoes based on 43 reviews, with a weighted average of 7.4/10. The site's consensus stated: "Those unfamiliar with Alejandro Jodorowsky's style may find it overwhelming, but Santa Sangre is a provocative psychedelic journey featuring the director's signature touches of violence, vulgarity, and an oddly personal moral center."

Accolades
The film was screened at the V Muestra de Cine Mexicano en Guadalajara where several groups of people left the room during the screening.

Santa Sangre is considered a cult movie and the restored print of the film was screened in 2008 Cannes Classics.

It was also screened during Locarno Film Festival 2016 Histoire(s) du cinéma: Pardo d'onore Swisscom Alejandro Jodorowsky.

title: Santa Sangre


text: Category:Physiologists by nationality

title: Category:Physiologists by nationality


text:
Harlan Mathews

Harlan Mathews (January 17, 1927 – May 9, 2014) was an American politician who was an appointed interim Democratic United States Senator from Tennessee from 1993 to 1994. He previously served in the executive and legislative branches of state government in Tennessee for more than 40 years beginning in 1950.

Early life and education
Harlan Mathews was born January 17, 1927, in Sumiton, Alabama, the son of John William Mathews and Lillian (Young) Mathews. In 1944, after high school, he enlisted in the U.S. Navy and served until 1946. Returning to Alabama, he graduated from Jacksonville State College (now Jacksonville State University) with a B.A. degree in 1949.

After graduating, Mathews obtained a master's degree in public administration from Vanderbilt University in 1950. He began work on Governor Gordon Browning's planning staff. When Frank G. Clement was elected governor in 1954, Mathews moved to the state's budget staff. A year after beginning his service as commissioner of finance and administration in 1961, he completed his law degree in 1962 from the YMCA Night Law School, now Nashville School of Law.

Early political career
Mathews joined the staff of the governor of Tennessee in 1950, serving governors Gordon Browning, Frank G. Clement and Buford Ellington. From 1961-1971 he served as commissioner of finance and administration.

In January 1971, Mathews left the cabinet and entered the private sector for two years, working for Amcon International in Memphis. In 1973, he became the legislative assistant to longtime Tennessee Comptroller of the Treasury Bill Snodgrass. In 1974, Mathews was elected state treasurer by the Tennessee General Assembly after his predecessor, Tom Wiseman, resigned to run for governor. The Tennessee General Assembly elected Mathews to his first full two-year term as treasurer in 1975, where he served until January 1987, when he became deputy to Governor Ned R. McWherter.

U.S. Senate
In 1993, Tennessee Governor Ned McWherter appointed Mathews to the U.S. Senate following the resignation of Al Gore, who resigned to serve as Vice President of the United States. Upon appointing Mathews to the senate, McWherter announced Mathews’ role would be one of caretaker, to allow those who wanted to run for the position to prepare their campaigns.

In mid-1993, Mathews expressed a desire to run in November 1994 for election to the remainder of Gore's senate term. "Hardly a day goes by that I don't get encouraged to get in there and offer myself" for next year's election, he said in July 1993. Mathews ultimately decided not to run in the special election and in December 1994, after Fred Thompson was elected to the seat, Mathews left office and resumed a law practice in Nashville, Tennessee.

Death
Mathews died of brain cancer on May 9, 2014, at a hospice in Nashville. He was survived by his wife, Pat, and two sons. A third son, Richard Mathews, preceded him in death.

title: Harlan Mathews


text:
Vukašin of Serbia

Vukašin Mrnjavčević (Вукашин Мрњавчевић, ; c. 1320 – 26 September 1371) was King of Serbia as the co-ruler of Stefan Uroš V from 1365 to 1371. He was also a nobleman. Principal domains of Vukašin and his family were located in southern parts of medieval Serbia and northwestern parts of the modern region of Macedonia. He died in the Battle of Maritsa in 1371 with his brother, Jovan Uglješa.

In folk tradition, Vukašin is referred to as a usurper and, wrongly, the murderer of Tsar Uroš. He was often considered de facto ruler of Serbian Empire during the reign of Uroš.

Background
According to 17th-century Ragusan historian Mavro Orbini, his father was a minor noble named Mrnjava from Zachlumia, whose sons Vukašin and Uglješa Mrnjavčević were born in Livno in western Bosnia. Some of Orbin's historical accounts are based on oral traditions of his time, but a 1280 Ragusan document mentions a Mrnjan as a nobleman from Trebinje, a town in Travunia in the vicinity of Zachlumia. The same Mrnjan is mentioned again in a 1289 charter as a treasurer of the Serbian queen Helen of Anjou. After Zachlumia was annexed by Bosnia in 1326, the family of Mrnjan, or Mrnjava, could have moved to Livno. Possibly the family supported Serbian Emperor Dušan's invasion of Bosnia in 1350, as did other Zachlumian nobles, and fearing punishment, emigrated to Serbia when the war was about to start. In favor of Zachumlian or Travunian origin of Vukašin also speaks the inscription on the tomb in a church in Ohrid, where certain Ostoja Rajaković of the Ugarčić clan (died 1379) is referred to as a cousin of Vukašin's eldest son Marko. The Ugarčić clan is attested in contemporary sources as inhabiting the region of Trebinje.

After Serbia had expanded southwards into Macedonia, the local feudal lords—Greeks—were replaced with Serbs, many of whom were from Zachlumia and Travunia. Around 1350 Emperor Dušan appointed Vukašin the župan (district governor) of Prilep in Macedonia. From then on Vukašin rapidly rose, and was one of the most dominant Serbian nobles at the time of the sudden death of Dušan in 1355. He was given the title of despot by Dušan's successor Emperor Stefan Uroš V. In 1365 he was crowned King of the Serbs and Greeks as the co-ruler of Emperor Uroš. He ruled over an area which included Prizren, Skopje and Prilep, and had good relations with his brother, Despot Jovan Uglješa who ruled an area around Ser. Later he became strong enough to disobey Uroš. By 1369, as Uroš was childless, Vukašin designated his eldest son Prince Marko as heir to the throne, with the title of "young king".

In 1370 he contributed to the monasteries of Mount Athos and prepared a war against the Ottoman Empire, which his brother supported. Vukašin was to attack Trebinje in June 1371 but it was never carried out. In September 1371, he established a coalition with his brother against the Ottomans and advanced. The Serbian army of the coalition numbering ca. 70,000 men met the Ottoman army led by beylerbey of Rumeli Lala Şâhin Paşa at the Battle of Maritsa on 26 September 1371 where superior Ottoman tactics won over, outnumbering the coalition army. The Ottomans attacked the Serbian Army while they rested and Vukašin's forces were routed and himself killed during the battle.

Family
With his wife Alena (Old Cyrillic: Алѣна), Vukašin had at least five children:
 * Marko Mrnjavčević
 * Andrijaš Mrnjavčević
 * Dmitar Mrnjavčević
 * Ivaniš Mrnjavčević
 * Olivera Mrnjavčević
 * Jelisanta
 * Jelena, married to Rajko Moneta

In popular culture
Brian Aldiss - published an alternative-history fantasy story "The Day Of The Doomed King" about King Vukašin.

title: Vukašin of Serbia


text:
Talk:Cryptographically secure pseudorandom number generator

One-time pads and CSPRNG
in One-time pad it is stated,

If the key is generated by a deterministic program then it is not actually random and should not be used in a one-time pad cipher. If so used, the method is called a stream cipher;...

which, i beliefe, is true!

Consequently

Many aspects of cryptography require random numbers, for example:

...   * One-time pads ...

as stated in this article is false.

Stream cipher might be the right here! --sig

 * Thanks for keeping an eye out for this sort of error. Certainly it is true that one-time pads is one of the applications in cryptography which require random numbers. However, I don't think the article is suggesting that a CSPRNG should be used for that application, but rather starting with a discourse about the use of randomness within cryptography in general. In fact, it explicitly says, "in the case of one-time pads, the information theoretic guarantees only hold if the random stream is obtained from a true random source.". — Matt 15:12, 13 Oct 2004 (UTC)

Special Types
I'm not sure if Hotbits counts as a "special type" or not - but if so it should be mentioned. It uses the unpredictability of radioactive decay to generate actual random numbers. I don't know if it can be said to be specifically designed for cryptography. Certainly, from a security perspective, you'd need the actual device in your secure network, and not access the numbers over the web. - Vedexent (talk) - 16:26, 18 November 2006 (UTC)

 * No, because it isn't pseudorandom; it is genuinely random. Of course, it may still fail to be cryptographically secure; true random number generators often fail the next bit test. Also, they generally aren't reproducible, which makes them useless for many applications. Ben Standeven 04:43, 3 February 2007 (UTC)

I am concerned to see that /dev/random is listed as if it were a Cryptographically secure pseudorandom number generator. The Billion bit test has found multiple uniformity flaws in a number of /dev/random implementations. In fact, I have never found a /dev/random implementation that did not suffer from at least 1 uniformity flaw, except those /dev/random implementations that bypassed the standard /dev/random driver code and directly accessed a Cryptographically sound hardware source.

The sited page lists observed flaws in the FreeBSD 5.2.1, Solaris 8 patch 108528-18, Linux 2.4.21-20, OS X 10.3.5 implementations of /dev/random. Not listed are a number of more recent tests under RedHat Linux, OS X, FreeBSD, and others. Should /dev/random be listed among the Cryptographically secure pseudorandom number generators given this consistent track record of uniformity flaws? chongo (talk) 03:38, 3 July 2009 (UTC)

Longest page name
Does anyone know if this page has the longest article name in Wikipedia? (Not counting articles like lists, categories, etc.) — SheeEttin {T/C} 19:20, 1 June 2007 (UTC)

 * Definitely not. This title is a mere 54 characters long; I've came across this one which has 78 characters: Tarquin Fin-tim-lin-bin-whin-bim-lim-bus-stop-F'tang-F'tang-Olé-Biscuitbarrel. :) -- intgr #%@! 12:33, 2 June 2007 (UTC)

Does counter + block cipher satisfy the requirements given in the article?
From the article:

Every CSPRNG should withstand 'state compromise extensions'. In the event that part or all of its state has been revealed (or guessed correctly), it should be impossible to reconstruct the stream of random numbers prior to the revelation.

and

A secure block cipher can be converted into a CSPRNG by running it in counter mode. This is done by choosing a random key and encrypting a zero, then encrypting a 1, then encrypting a 2, etc. The counter can also be started at an arbitrary number other than zero.

What is the state here? The obvious answer seems to be the value of the counter, but I might have misunderstood something. If so, how does it satisfy the requirement that "it should be impossible to reconstruct the stream of random numbers prior to the revelation" in the event of state compromise? --SLi 12:53, 15 September 2007 (UTC)

 * I agree with you that this needs clarification. If you view that state as 'counter + key' than it is obviously not resistant against a state compromise. If you view the state as just the counter, then it might well be. In any case, it needs a citation. Sander123 08:38, 17 September 2007 (UTC)

 * The key is absolutely a part of the state of the PRNG, not just the counter. I have added a dubious tag, since the article is inconsistent. Darco (talk) 17:54, 10 April 2020 (UTC)

 * Also, strictly speaking, it doesn't satisfy the next-bit test, either. For example, if the previous block_size*2-1 bits are 1, then the probability that the next bit will also be 1 is 0%. Darco (talk) 18:01, 10 April 2020 (UTC)

 * i think the article is two minded about csprngs. in reality there is the formal definition and there are real world implementations that only partially satisfy the requirements. the formal part of the article fails to mention this, but some of the practical examples violate strict requirements. there are two ways out of this: either we need to widen the definition to contain both ideal csprngs and "wild" csprngs, or clearly explain in the examples section that these implementations fail to satisfy all requirements, but used anyway for practical reasons. i personally think ideal csprngs and practical csprngs would fit nicely in one article, only the distinction must be made explicit and clear. Krisztián Pintér (talk) 10:07, 12 April 2020 (UTC)
 * The article tries to explain the CTR_DRBG construct (per NIST terminology), but glosses over the details, thus the confusion. The counter (CTR) mode is only used to "generate" a single  random number (say, 4 invocations with a 128-bit block for total of 512 bits). After that, an "update" is performed (also using the CTR mode) that regenerates both the key and the counter value. As a result, if Eve gets hold of the new state, she will have to reverse the block encryption to get the previous values, which is assumed to be impossible. So (1) the text as-is is correct (2) It can be improved by adding the details (for example, per NIST SP 800-90A). And yes, key is very much part of the state here. Dimawik (talk) 23:25, 30 August 2023 (UTC)
 * I have replaced the confusing text (also incorrect in a case of using the streaming cipher) with short sentences pointing to NIST/ANSI constructs that are actually used in practice. This text can be easily expanded based on, say, SP 800-90Ar1. Dimawik (talk) 23:47, 30 August 2023 (UTC)

The key is not considered part of the state. It is part of the secret. No cryptographic scheme survives its keys/seeds/secret being discovered.

The state is that which can potentially be tractably discernible from external context. For example, if used as a stream cipher, a block cipher CPRNG in counter mode can have its count discovered if the number of bits encrypted is known, or in output feedback mode can have its last block discovered because its plaintext is known.

I'm not sure I follow regarding it not passing the next-bit test. Note that it only has to resist the next-bit test for a polynomial time adversary. Failing the test if the adversary has access to e.g. output length exponential in the block size is expected. 47.203.176.153 (talk) 09:12, 26 August 2023 (UTC)

 * Key here is a part of the state, see my reply above. Dimawik (talk) 23:26, 30 August 2023 (UTC)
 * I am almost certain the construction being described was not CTR_DRBG but rather the counter mode described by most introductory cryptography sources (e.g. https://joyofcryptography.com/pdf/chap6.pdf, construction 6.2) which in particular assume the key is secret and do not have any forward secrecy assurances if the key is compromised. In any case, in lieu of a more detailed account of the concerns with this construction motivating the design of CTR_DRBG, reference to CTR_DRBG is an improvement. 47.203.176.153 (talk) 10:34, 11 September 2023 (UTC)
 * I absolutely agree with you: the original text was describing an approach that used a pure CTR mode as a PRNG. However, the article is about a practical device that is both complex and critical for the security. In such a situation trust is of utmost importance, this trust more or less requires a validation by an independent party. As of this writing, CTR_DRBG will pass such validation, while the simple CTR construct will not and thus is not state-of-the-art. Therefore, the simple CTR approach belongs in the History section (if there are reviews pointing to its previous use) or should not be mentioned at all (my position). There are thousands of possible PRNG designs, almost all of them are not suitable for the cryptographic applications (as an obvious deficiency of the pure CTR construct I would point to its great susceptibility to the side-channel attack). Dimawik (talk) 17:11, 11 September 2023 (UTC)

State Compromise Extensions
Question, could "Every CSPRNG should withstand 'state compromise extensions'." be changed to "Every CSPRNG, for which the intended use is dynamic generation of pseudorandom bits, should withstand 'state compromise extensions'."? How is anyone going to compromise the state and "retrodict" the previous or future bits if the use is to a) seed a PRNG, b) generate and store the bits in a large binary file and c) shred, burn or otherwise destroy any evidence of the PRNG used in step a? — Preceding unsigned comment added by 76.181.226.94 (talk) 16:02, 12 February 2012 (UTC)

 * CSPRNG is a practical device. Design hypothesized here will not pass any modern validations and thus cannot be truly considered a CSPRNG. Dimawik (talk) 17:14, 11 September 2023 (UTC)

but this isn't pseudo...
One design in this class is included in the ANSI X9.17 standard (Financial Institution Key Management (wholesale)), and has been adopted as a FIPS standard as well. It works as follows:

each time a random number is required:
 * input: a 64 bit random seed s, and a DES EDE key k.
 * using current date/time information D (in the maximum resolution available), compute I = DES_k (D)
 * output x=DES_k(I xor s), and update the seed s to DES_k(x xor I)

It has been suggested that this algorithm would be improved by using AES instead of DES (Young and Yung, op cit, sect 3.5.1) But unless the times at which D is retrieved are chosen deterministically, that's not a pseudorandom number generator. For example, you can't retrieve the same sequence twice by starting from the same seed (unless you store all the values of D obtained during the first generation, that is). Essentially, you're just applying software whitening to the system clock. Thus I'm removing this example from the article. -- A r m y 1 9 8 7 ! ! 16:04, 11 July 2008 (UTC)

 * The 64 bits output at each stage is more than the entropy that can be read off of computer system clocks, even if they have microsecond resolution, which most don't. So, yes, this generator is not fully random.--agr (talk) 17:28, 11 July 2008 (UTC)
 * Yes, but it isn't fully pseudorandom, either. According to Pseudorandom number generator, "[t]he sequence is not truly random in that it is completely determined by a relatively small set of initial values, called the PRNG's state", a condition which the generator described above doesn't fulfill. (I assume that in that definition "relatively small" means "of size O(1)", whereas the generator above requires O(N) bits of input to produce N bits of output.) So, it isn't fully random, but it is "partly" random. (Imagine a generator which uses radioactive decay to produce random bits, but bit 0 has probability 0.999 and bit 1 has probability 0.001; its entropy is much less than the size of the output, but this doesn't mean it is a pseudorandom number generator, right?) -- A r m y 1 9 8 7 ! !  10:29, 12 July 2008 (UTC)

 * Other designs mentioned, such as Yarrow, are not pure PRNGs either, yet the literature refers to them as PRNGs. I moved the X9.17 description to special designs and edited the text to make these distinctions clearer. --agr (talk) 10:55, 13 July 2008 (UTC)
 * Right. I hadn't even noticed the lead section, "When all the entropy we have is available before algorithm execution begins, we really have a stream cipher. However some crypto system designs allow for the addition of entropy during execution, in which case it is not a stream cipher equivalent and cannot be used as one. Stream cipher and CSPRNG design is thus closely related." -- A r m y 1 9 8 7 ! ! 09:22, 14 July 2008 (UTC)

Edit with summary: "see talk page"
I just edited the following original text:

The next-bit test is as follows: Given the first k bits of a random sequence, there is no polynomial-time algorithm that can predict the ( k +1)th bit with probability of success higher than 50%.

I changed "higher" to "better". In fact, I could have changed it to "other". If an algorithm A( n ) can predict the n th bit with a success rate r that is less than 50%, then an algorithm B( n ) can be constructed (with trivial effort) to predict bits with a success rate greater than 50%, namely a rate of 1 - r. This is done simply by defining B( n ) = NOT A( n ). Therefore, if any prediction algorithm can be discovered that has a probability of success that is not exactly 50%, then one can be derived from it that has a probability greater than 50%. This leads to the corollary that any algorithm whose success rate is not exactly 50% is better than one with a success rate of exactly 50%.

Another way to look at this is that 50% success in predicting binary values represents absolutely no information. Anything else represents some information. (If we flip the 50%-likely-correct preditions, 0 to 1 and 1 to 0, we still have exactly the same probability of correctness: 50%. So the prediction algorithm has told us nothing.)  The next-bit test requires that we get no information about the next bit of the random sequence from the current bit and a polynomial-time prediction algorithm. (I say this not from any knowledge of the test or of the definition of a CSPRNG, but merely by applying basic logic and mathematics to the information already I found present in the article.) 71.242.7.208 (talk) 19:57, 5 June 2009 (UTC)
 * I believe this discussion is correct, although the current wording is probably clearer (either "higher" or "better" is fine). Dcoetzee 22:37, 5 June 2009 (UTC)

CSPRG vs. CSPRNG vs. CSPRBG
I copy this from Talk:Pseudorandom number generator. I think the article should rather discuss cryptographically secure pseudo-random generators (CSPRGs) in general, and then introduce cryptographically secure pseudo-random number generators (CSPRNGs) and cryptographically secure pseudo-random bit generators (CSPRBGs) as sub-classes. Thoughts? Nageh (talk) 08:52, 21 May 2010 (UTC)

 * Is there even any significant difference between these terms? Can't you always construct one from the other? And please list sources. -- intgr [talk] 09:05, 21 May 2010 (UTC)

 * What do you mean by significant? It's a matter of definition. Yes, you can construct PRNGs from PRBGs and vice-versa, but that's not the point here. And hey, this is a talk page! I am trying to discuss an issue, so we do you want me to provide sources? (I have some, so if you insist.) Nageh (talk) 09:11, 21 May 2010 (UTC)

 * And if you look at Talk:Pseudorandom number generator, you'll see that I am asking for a reference where this is addressed and defined adequately. Why am I writing on a talk page, huh? Nageh (talk) 09:15, 21 May 2010 (UTC)

/dev/random
I don't understand this.

According to its page, /dev/random is true random. Whereas /dev/urandom is a PRNG sourced from /dev/random. Is that in dispute? WMC 23:18, 23 December 2010 (UTC)

 * Please consider my subsequent edit, in which I deleted the whole line. The one reason is that /dev/random is not a true PRG – "true" PRGs can only be generated from physical noise, radioactive decay, and the like. /dev/random emulates a true random PRG, and by measuring the entropy it attempts to construct a CSPRG. The second reason is that /dev/random is already mentioned in the first bullet on the Yarrow algorithm. The third is that /dev/urandom is not a CSPRG (which this article is about), but merely a PRG with inferior statistical properties (precisely because it does not block to wait for sufficient entropy). HTH, Nageh (talk) 09:37, 24 December 2010 (UTC)

Just for info, it seems from the documentation and from comments in the code that /dev/urandom is intended to still be cryptographically secure when there is insufficient new entropy for it to be truly random, in that it recycles old entropy by feeding SHA1 hashes into the pool - though I am prepared to believe if you say that such an algorithm isn't secure enough by today's standards. (By the way, I don't intend to edit the article again - I find it interesting but I think I've got out of my depth, so sorry if my earlier edit was wrong.) Scil100 (talk) 00:26, 25 December 2010 (UTC)

 * I will quote from man urandom:
 * "A read from the /dev/urandom device will not block waiting for more entropy. As a result, if there is not sufficient entropy in the entropy pool, the returned values are theoretically vulnerable to a cryptographic attack on the algorithms used by the driver."
 * If it is (theoretically) vulnerable to a cryptographic attack it cannot be a cryptographically secure pseudo-random generator. It may still be suitable for some cryptographic applications like key derivation, for which strong CS properties may not be required. But then it is merely a PRG.
 * Using a cryptographic hash function (e.g., SHA) to extract randomness from old entropy is a good approach for minimizing the danger of an exploitable weakness in randomness. But it provides no strict guarantees: Cryptographic hash functions, though often treated so in theoretical analysis, are not regarded as having (strong) pseudo-random properties. For example, The Handbook explicitly regards hash-based pseudo-random generators as not being cryptographically secure. And when it comes to randomness extraction, HMAC and CMAC have been proven to be secure randomness extractors, a result that is not known for a simple cryptographic hash function. Nageh (talk) 12:09, 25 December 2010 (UTC)

 * Oh, and sorry, Scil100, for my strong words in one of my previous edit summaries. Nageh (talk) 12:12, 25 December 2010 (UTC)
 * Thanks. No worries. It was my fault entirely for trying to writing about stuff I don't know enough about. Scil100 (talk) 19:16, 27 December 2010 (UTC)
 * "If it is (theoretically) vulnerable to a cryptographic attack it cannot be a cryptographically secure pseudo-random generator"
 * I disagree. The term "CSPRNG" is used to classify PRNGs into ones that are intended for cryptography and ones whose output is merely statistically random. Even if a CSPRNG is broken, it's still a CSPRNG — like a broken cryptographic hash function is still a cryptographic hash function. /dev/urandom is certainly designed to be cryptographically strong.
 * That may be the current Wikipedia definition (from the lead sentence), but perhaps it is not correct. According the Handbook of Applied Cryptography chapter 5, definition 5.8 (and assuming that CSPRNG and "... Bit Generator" are equivalent for this purpose) a CSPRNG/CSPRBG is  (very loosely) one whose output cannot be determined given all the previous outputs. Ie it is defined by the practical indeterminability of its output, NOT what purpose the output is intended for. Mitch Ames (talk) 08:48, 27 December 2010 (UTC)

 * And the collection of entropy is unrelated to a PRNG itself. Every PRNG requires entropy input in order to be useful. Every PRNG is insecure if the input is predictable to an attacker. The PRNG behind /dev/urandom is no different, it simply works with all the entropy it has.
 * I will also point out that the entropy estimator behind /dev/random has no academic basis or review; there is little evidence that it's helpful at all. If that entropy esimator fails, /dev/random is no better than /dev/urandom. However, in regular computers with real hard disks, there is always sufficient entropy available. The question is only about diskless embedded devices with no real entropy sources. -- intgr [talk] 22:38, 26 December 2010 (UTC)

 * It's not true that every PRNG requires entropy input in order to be useful. There are cases where it is useful to be able to easily regenerate the same set of pseudo-random data multiple times. In these cases I might deliberately seed the algorithm with the same start value. I've done this in the past when testing data encryption or hashing algorithms. I pass in some "random" data and record the output. Then I tweak the algorithm - eg optimising for speed or code size - then run it again with the same data and check that I get the same result. Of course I would run the tests with the sample data provided in the standards for the algorith, but sometimes it's good to see that the algorithm produces the same output (before and after optimization) for any arbitrary data. A deterministic PRNG is an easy way of creating relatively large amounts of reproducible data. Mitch Ames (talk) 09:02, 27 December 2010 (UTC)

Re Intgr: The term CSPRG is used to distinguish PRGs for which no polynomial-time distinguisher exists (or is unlikely to exist given some computational hardness assumption) from those PRGs for which a polynomial-time distinguisher does or may exist and which only has some desirable statistical properties. This does not mean that the output of PRGs is not suitable for specific cryptographic purposes, such as key derivation and salts. However, it is less desirable to use such "insecure" PRGs for key generation.

Note that there is no globally accepted definition for a PRG, and cryptographers and mathematicians often equate PRG := CSPRG.

Now regarding your observation that a broken cryptographic primitive is still called cryptographic. One reason is that it is odd to relabel a primitive after it is broken. The difference here is that it is said from the outset that for /dev/urandom a cryptographic attack may exist. If there is not even faith in that no practical distinguisher exists then it cannot be a CSPRG by definition. (But, it may still be a suitable PRG.)

Yes, collecting entropy is unrelated to a PRG. It was my impression from reading on man /dev/(u)random that the device emulates a "true" random generator in which case it has to continually collect new entropy. Now, insufficient entropy says nothing about its (in)security as a CSPRG, and I based my statement that /dev/urandom is not CS solely on the warning of a theoretical attack in the man page. Particularly, I still left /dev/random as a CSPRG in the article. (Yes, the situation may change if the entropy estimator gets broken, in which case both designs will not be CSPRGs.) Nageh (talk) 12:14, 27 December 2010 (UTC)

 * Different versions of Unix-like operating systems may implement /dev/random in different ways. I believe on OS-X uses yarrow and is the same as /dev/urandom. In any case, it would be helpful if this article made clear the different meanings of "Cryptographically secure pseudorandom number generator". --agr (talk) 16:27, 27 December 2010 (UTC)

Hyphenation
Should there be a hyphen in Cryptographically-secure? — Preceding unsigned comment added by 198.208.251.22 (talk)

 * I believe not, most sources don't have a hyphen/dash there. -- intgr [talk] 07:46, 14 April 2015 (UTC)

CSPRNG libraries and implementations
It seems like this page should have a section discussing CSPRNG libraries and implementations. Or does that exist in a separate article? If so, does that article already exist? Risc64 (talk) 07:03, 30 December 2015 (UTC)

DUHK (Don't Use Hard-coded Keys) is a vulnerability that affects devices using the ANSI X9.31 Random Number Generator (RNG) in conjunction with a hard-coded seed key.
https://duhkattack.com/ 441ac5d1 (talk) 08:53, 24 October 2017 (UTC)

Multiple senses of CSPRNG
There are a few senses of CSPRNG at play here:

 * An algorithm to turn a random seed into an infinite stream (AES-CTR, Blum-Blum-Shub, etc.). The first half of Definitions and the first 2/3 of Designs seem to talk about those.
 * A design such as Yarrow or Fortuna. Unlike bare ciphers, these are designed to accept lots of entropy bits that are imperfectly random, to accept entropy at random times, and to do their best to minimize the scope of impact even if internal state is compromised (vs. an AES-CTR key leak obviously revealing all past/future random numbers).
 * A concrete function like CryptGenRandom, arc4random, or I guess ANSI X9.17: these are backed by some design, whether Yarrow, Fortuna, or something the authors put together themselves, and also by some specific code for gathering and maybe estimating entropy.

The weird thing is no one really messed up in adding their piece, because "CSPRNG" is actually used to mean each of those things, but it seems helpful to call out the distinctions. And they really are distinct concepts. AES-CTR is not just the same kind of thing as Yarrow but weaker; the two actually take different kinds of input at different times. And the specific functions like CryptGenRandom involve security-critical things that are abstract/assumed in the Yarrow and Fortuna designs, like the entropy sources--an implementation can fail despite even if built on a solid design if the inputs are bad enough. — Preceding unsigned comment added by 76.103.246.130 (talk • contribs)
 * (1) "CS" here actually has a quite precise meaning and the simple AES-CTR does not meet the requirements. The first definition is not thus not "CS" and should not even be mentioned here. (2) I see no practical difference between an "algorithm" and "concrete function"; algorithms are always expressed in some language, and C/C++/C#, etc. are not special, just not always as readable as pseudocode. (3) The source of entropy is not part of "PRNG". Thus, there is essentially a single subject here: an algorithm that provides cryptographically secure random numbers when seeded with an unpredictable bit string. The existing text should simply be trimmed to delete the "simple" (and wrong) designs and possibly expanded to describe the actual CSPRNG algorithms (there are not too many of these). The "simple" approaches can only be listed in the "these are not CSPRNG" section, if a source for that statement can be found. --Dimawik (talk) 17:50, 31 August 2023 (UTC)

"Special designs"
What does "special" even mean in the name of the "special designs" section? It lists a bunch of generators that fall into the type described the cryptographic section, but also one that does not fall into either.
 * "Designs based on cryptographic primitives" should include AES CTR DRBG, the two RC4 things (ISAAC, arc4random), and the two ChaCha20 things.
 * ANSI X9.17 probably also falls in the bucket. Yarrow and Fortuna use a hash function somewhere, so arguably they also count.
 * CryptGenRandom also counts as using SHA-1, if we follow the description and the "FIPS 186-2 appendix 3.1" reference. It would probably fall into the same bucket as Yarrow in how it mixes things for the seed.
 * Well, and that's it! The only thing left is the one "linear-feedback shift register" (LFSR). That really doesn't fall into any of these buckets. That thing should be removed, in my opinion, because there is no claim of cryptographic security from the author. Just because something passes the statistical test doesn't mean someone can't predict the output.

At present we have a sentence that says "the last often introduces additional entropy when available". I don't believe "special-purpose" is the best word for describing this kind of difference. I think the categories from 76.103.246.130 also ties into this.

--Artoria2e5 🌉 10:59, 4 March 2024 (UTC)

 * So I decided to instead call them "practical" and changed the distinction from "mixes in entropy" to "handles the seeding for you". I think that works better, though maybe a better word can be found. Artoria2e5 🌉 11:59, 4 March 2024 (UTC)


text: Category:Psychiatrists by nationality

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Category:Golf associations

See also professional golf tours.

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Quenelle

A quenelle is a mixture of creamed fish or meat, sometimes combined with breadcrumbs, with a light egg binding, formed into an egg-like shape, and then cooked. The usual preparation is by poaching. Formerly, quenelles were often used as a garnish in haute cuisine. Today, they are more commonly served sauced as a dish in their own right. Similar items are found in many cuisines.

By extension, a quenelle may also be another food made into a similar shape, such as ice cream, sorbet, butter, or mashed potato quenelles.

Etymology

The word quenelle is attested from 1750. The commonly accepted etymology is that it derives from the German Knödel (noodle or dumpling).

Quenelles de brochet
Lyon and Nantua are famous for their quenelles de brochet (pike quenelles), often served with sauce Nantua (crayfish sauce) or sauce mousseline (cream sauce) and run under a grill. The classic dish of quenelles de brochet Nantua or simply quenelles Nantua consists of pike quenelles with sauce Nantua, both pike and crayfish being specialties of the Nantua area. Pike quenelles were invented by a chef named Bontemps to deal with the pike's "multitude of long, fine, forked bones".

Quenelles de brochet are prepared in many ways, but most recipes first prepare a panade, essentially a thick white sauce, then combine the panade with fish, and put the mixture through a sieve such as a tamis, yielding a forcemeat. The quenelles are shaped from the forcemeat and then poached. They may be served sauced and grilled, or with a variety of sauces.

title: Quenelle


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User:Michael Drüing

About Me
Hi. I'm Michael Drüing (that's Michael Drueing for you non-Umlaut people out there) from Reutlingen, Germany.

Here are some chess games I'm currently playing. Wikipedia's chess template is simply great! :)

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title: User:Michael Drüing


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Copyright law of Greece

The copyright laws in Greece are part of the frame of laws which are constantly being adapted to the guidelines of the European Union.

The enforcement of the copyright laws varies from case to case. Greece has attracted attention because of its extended copyright infringement of software and music. The Greek government has tried to impose countermeasures such as the prosecution of those who produce or consume unauthorized material, with questionable results.

title: Copyright law of Greece


text:
User talk:Svvvn

Hi, thanks for your comment at Talk:Cryptographically secure pseudo-random number generator, and Welcome to Wikipedia! If you want to sign your name, the mechanism is to type four tildes in a row, like this: ~, and the software will substitute your signature and the time/date. — Matt 15:13, 13 Oct 2004 (UTC)

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User talk:Mark.deane

Deceptive edit summaries and spamming are not acceptible behaviour. Knock it off. —Rory ☺ 15:14, Oct 13, 2004 (UTC)

title: User talk:Mark.deane


text:
Talk:Nonlinear regression

Questions
I'm moving some questions from the article page to the talk page.

 * --is there a rigorous theory of when analytic solutions are possible?
 * --are there some models that have no analytic solutions, but have iterative solutions that are guarenteed to converge to the global optimal?

These can be addressed in the article text at some point. Wile E. Heresiarch 15:15, 13 Oct 2004 (UTC)

The clever graphic showing polynomial regression is inappropriate, since polynomial regression is a special case of linear regression, not nonlinear regression. A model is linear if the unknowns are a linear function of the knowns. In this case the Xs and Y are the knowns and the betas are the unknowns, so having powers of X in the predictors makes no difference. It is still linear. Blaise 10:19, 26 March 2006 (UTC)

 * Good lord, what an unfortunate term then. It really shouldn't be called "linear" if it isn't simply meant to imply a linear relationship between x and y.  If I hadn't chanced upon these Wikipedia articles, I'd continue to have no idea about these peculiar term usages, which I had thought I knew for 25 years. 207.189.230.42 (talk) 08:05, 25 May 2009 (UTC)

Some Problems with the Material added, on Monte Carlo
The use of Monte Carlo deserves consideration. However, as it seems to me, the material just added has several problems. In essence, this is kind of jumping the gun on full development of the article.

1. There is not yet, and needs to be, a section on inference for nonlinear regression. Statistical inference is what distinguishes nonlinear regression from curve fitting. Most procedures from linear regression have analogues in nonlinear regression. The mention of Monte Carlo would belong in that section. 2. I think you are talking about parametric bootstrap. Why not mention nonparametric bootstrap (ordinarily, resampling). 3. You have put in an unusual procedure when as yet there is no mention of the standard errors available in standard nonlinear regression software. 4. The title is not correct. The material suggested is about evaluating error, not about parameter estimation. I don't think Monte Carlo is used for parameter estimation. 5. The use of Monte Carlo simulation as described could be considered for many statistical models. The material is not specific to nonlinear regression. 6. Use of Monte Carlo to evaluate sampling error is an important procedure in practice. I would say we do need to review other articles to see that this is covered. For example, since such materials may be used by government statisticians, it is a service to the public to provide some material.

If these points are not addressed, I will most likely take a shot at them at some point. Dfarrar 21:34, 20 March 2007 (UTC)

Major revision
This article has been subject to a major revision which brings it into line with regression analysis and linear regression. The section on Monte Carlo has been removed, as it is wholly inappropriate; it has been replaced by a section on parameter statistics. Petergans (talk) 16:48, 23 February 2008 (UTC)

Linear Transformation vs. Linearization
The proper term for moving a function to a domain where it is linear is a linear transformation. Linearization almost always refers to approximating a function as linear for some bounded range. This is presented in the note:

"Linearization" as used here is not to be confused with the local linearization involved in standard algorithms such as the Gauss-Newton algorithm. Similarly, the methodology of generalized linear models does not involve linearization for parameter estimation.

I'm removing the note as it is no longer needed after the correction. I agree the note was very relevant and important when the term linearization was used.

Linear regression via Linear transform vs. non-linear regression
Someone had suggested that shifting a problem into a linear domain is unnecessary and not recommended. I would ask the author of that section to provide some basis for his assertion beyond referring to the linear transformation section which indicates that its fair as long as proper consideration is given to errors. Certain problems, where in datasets are very large or where time intervals are very short, such as in a feedback control system, can only be practically solved by linear regression. Proper weighting of data points can compensate for the transform and yield theoretically optimal results. —Preceding unsigned comment added by 198.123.51.205 (talk) 22:58, 13 June 2008 (UTC)
 * It is not necessary because there are so many nonlinear programs available, including the use of SOLVER in EXCEL. Once the system has been set up the nonlinear refinement is just as easy as the linear one. The size of the dataset is immaterial. The time required is hardly an issue with modern computers.
 * It is not reccommended because transforming the weights is subject to error as a linear transformation has to be assumed. The Lineweaver-Burk example cited later shows how dangerous the transformation can be. That example is not just of academic interest: enzyme kinetics are used in hospital path labs on samples from real patients. Petergans (talk) 07:49, 16 June 2008 (UTC)

 * I disagree that modern computers are fast enough or have large enough memories for the use of linear transformations to be deprecated. This makes the assumption that the user has no time limit for computation or that the user is working on a data set that can fit in the memory of a computer. When working with very large data sets, as often done in physics experiments and simulations, data can exceed several terabytes. Also keep in mind the Fourier and Laplace transforms are also linear transformation. In engineering, applying these linear transform before curve fitting is the rule rather than the exception. —Preceding unsigned comment added by 63.201.67.93 (talk) 09:50, 3 August 2008 (UTC)

== Is this a known problem in multiple non-linear Regression It Non linear regression used on most on Application in Textile research

I'm referring to linearly adding non-linear effects. For example:

f(x1,x2) = k + a log(x1) + b log(x2)+ b log (x3) If condition =k+a log (X1) +b log(X2) That

Now, suppose explanatory variables x1 and x2 are such that they have identical effects, with all else being equal. Suppose also that the quantities are such that they can be added (e.g. concentration of a greenhouse gas.) Then you have that a = b, so:

f(x1,x2) = k + a log(x1 + x2)

But then:

log(x1 + x2) = log(x1) + log(x2)

Which is absurd. So it seems to me that non-linear effects can't really be added linearly. I was just wondering if this is a known problem of multiple non-linear regression analysis. Joseph449008 (talk) 14:18, 31 December 2009 (UTC)

 * Your algebra is wrong. If a = b, then
 * a log(x1) + b log(x2) = a( log(x1) + log(x2) ).
 * There is nothing in that, that in any way implies that this is equal to
 * a log(x1 + x2).
 * How you reached that conclusion you haven't said. Michael Hardy (talk) 21:22, 31 December 2009 (UTC)
 * How you reached that conclusion you haven't said. Michael Hardy (talk) 21:22, 31 December 2009 (UTC)

 * I did not manage to explain myself then. It's a thought experiment. Suppose x1 and x2 are variables that have identical effects. Specifically, suppose they are greenhouse gas concentrations. To make it more obvious, suppose x1 is industrially produced CO2 and x2 is naturally produced CO2. Clearly, you can add x1+x2 and you get 'all CO2'. So the effect of the two combined can be expressed as k + a log (x1 + x2). Does that make sense? Joseph449008 (talk) 23:44, 31 December 2009 (UTC)

 * Or to explain it a different way, if x1 and x2 are interchangeable, and we accept that the non-linear effects can be added linearly, then the following expression should be valid, but isn't:
 * k + a log(100) + b log(100) = k + a log(1) + b log(199)
 * Joseph449008 (talk) 00:19, 1 January 2010 (UTC)

Michaelis–Menten model is a terrible example
Despite being a biochemist, I have a problem with the Michaelis–Menten model being used as an example. The Michaelis–Menten equation is a specific case of rectangular hyperbola and has its own jargon which is quite different from the standard mathematical jargon: this article is about a mathematical topic and not enzyme kinetics. Secondly, the example image given has a perfect fit which is a very poor example of regression. --Squidonius (talk) 00:31, 2 October 2011 (UTC) :: Also, that looks a lot like polynomial linear regression. In no way can anyone guess it is non-linear regression from a simple viewing of the image. NK (talk) 16:39, 18 July 2018 (UTC)

Equation parsing error
There is a problem with the last equation under the part "Regression Statistics". My web browser cannot convert it to PNG. I tried to fix it myself, but I failed. — Preceding unsigned comment added by Gustafullman (talk • contribs) 10:49, 7 October 2011 (UTC)
 * Thanks for reporting that. I've fixed it by adding some more braces {} to the LaTeX source for the equation. Appears this was due to a bug associated with the recent upgrade to the MediaWiki software. Qwfp (talk) 14:07, 7 October 2011 (UTC)

Grammar in opening paragraph
"... observational data are modeled by a function which [sic.] is a nonlinear combination of the model parameters and depends on one or more independent variables." What this actually means, in plain English, is that the model of the observational data is a function of its own parameters and depends on some variables; i.e. the phrase is meaningless. If we cannot write an introductory sentence that means anything then it would be less confusing if we were to remove it altogether. At the moment, all it is actually saying is: "In statistics, nonlinear regression is a form of regression analysis in which observational data are modeled by a function"; maybe we ought to leave it at that and forget about the ensuing word salad? (by 90.217.127.222)
 * You're right that the sentence is very weak. However, your two "plain English" translations have omitted the crucial word from the original: "nonlinear". People often have very strong opinions on article intros. So shall we draft a better sentence here, on the talk page, before changing the article?
 * Also, please sign your talk page posts using four tildes: ~ . Mgnbar (talk) 16:44, 4 May 2014 (UTC)

2017 December
Please forgive me, but I do not like this at all. Do you think somebody reading this is really going to get it and say "ah ha, got it" and go solve his problem with C#, visual basic or excel? I really do not think so. and what's with that "Regression statistics" section? It's a first order Taylor series expansion. Why doesn't it say that? — Preceding unsigned comment added by 64.207.224.40 (talk) 17:15, 14 December 2017 (UTC)

 * It's not a great article. Feel free to add the part about Taylor series, although another editor may complain that it is unsourced.

 * Part of the problem is that Wikipedia has many articles on closely related topics around regression and least squares. Did you follow the link to Non-linear least squares for more detail?

 * Another part of the problem is that Wikipedia is not a textbook. Another part of the problem, I think, it that you are underestimating the difficulty --- if you really want to write your own non-linear optimizer in Excel, based on the kind of rudimentary introduction that a Wikipedia article provides. Regards. Mgnbar (talk) 19:10, 14 December 2017 (UTC)

 * I added the note on Taylor series. In that section, is "this procedure" referring to a particular numerical approximation technique? AFAIK, this isn't an approximation intrinsic to non-linear regression. Scientific29 (talk) 05:16, 5 January 2018 (UTC)

title: Talk:Nonlinear regression


text:
User:Volk~enwiki

My name is Sergey Volchkov, I am from Ukraine

I study at Radiophysical Department of Ukraine Taras Shevchenko National University of Kyiv

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Aid agency

An aid agency, also known as development charity, is an organization dedicated to distributing aid. Many professional aid organisations exist, both within government, between governments as multilateral donors and as private voluntary organizations or non-governmental organisations. The International Committee of the Red Cross is the world's second oldest humanitarian organisation and is unique in being mandated by international treaty to uphold the Geneva Conventions. The Sovereign Order of Malta, established in 1099 as the Order of St. John of Jerusalem, has an unbroken tradition of over 900 years of hospitaller activities, continuing to this day. Even in its modern guise under international law, it was recognized at the Congress of Verona of 1822, and since 1834 headquartered in Palazzo Malta in Rome, decades before the Red Cross.

Aid can be subdivided into two categories: humanitarian aid (emergency relief efforts, e.g. in response to natural disasters), and development aid (or foreign aid), aimed at helping countries to achieve long-term sustainable economic growth, with the aim of achieving poverty reduction. Some aid agencies carry out both kinds of aid, whilst others specialise on one aspect.

With a lack of oversight within the Charity realm, there are Non-development assistance committees, and development assistance committees. Within the last few decades DACs have been the main character in the research on the charity's effectiveness. Through vigorous study we will be looking into both forms of charity and there effectiveness based on five factors.( transparency, overhead costs, aid specialization, selective allocation, and effective delivery channels) to see which form of the committee is most effective. (Dreher & Fuchs, 2015;) explain that both companies apply most aid to their country of origin. Although DAC agencies have more refined and easy obtain records showing their reporting and the lowest overhead costs, they engage in much worse effective aid practices in the remaining four factors.( Brech & Potrafke, 2014; Dreher et al., 2009; Fleck & Kilby, 2010; Frot et al., 2014; Fuchs et al., 2014; Kuziemko & Werker, 2006; Maizels & Nissanke, 1984; Neumayer, 2003). All in all, both DAC and Non-DAC have flaws; neither is clean from government pressure and lobbyist money ( Roodman (2004), Knack (2001). With further research on donor failure when it comes to meeting YoY standards we can find whether or not donors give because of self-interest

title: Aid agency