*MathWorld* Q&A

- Contacting the site's maintainers
- Problems with display or printing
- Site organization and conventions
- Details about the site
- Copyright and access restrictions
- Is the material on
*MathWorld*copyrighted? - Is the material on
*MathWorld*available in formats other than HTML? - Why do I get "Access Denied to IP Address xxx.xxx.xxx.xxx"?
- Why do I get "Access Denied to Browser Agent xxx"?
- Can I get my own copy of
*MathWorld*? - May I host a mirror site or create a personal mirror?

- Is the material on
- Citing and linking to
*MathWorld* - Finding more information
- I need to know more about or have a homework assignment on
*X.*Can you help? - Why couldn't I find
*X*in*MathWorld*? - Can I hire you as a consultant on mathematics?
- Can you suggest student projects based on
*MathWorld*? - Do you provide on-line course material, study guides, lesson plans, etc.?
- Can you suggest books, classes, or colleges that will help prepare me for a career in mathematics?
- I would like a book or copy of a journal article cited on
*MathWorld*. Can you provide one? - Can you provide information on how to publish a new mathematical result?
- Is
*MathWorld*available in languages other than English?

- I need to know more about or have a homework assignment on
- Specific Questions

**Q:**How do I submit a math fact I couldn't find in*MathWorld*?-
**A:**Specific math facts or definitions to be added to*MathWorld*are welcome and can be submitted via the online contribution form or by sending postal mail to the following address:*MathWorld*

Wolfram Research, Inc.

100 Trade Center Drive

Champaign, IL 61820-7237

USA

fax: +1-217-398-0747All contributions will be reviewed for correctness and suitability. Material should be specific, concise, verifiable, and preferably useful and interesting as well. References to published literature are especially helpful.

Figures, if included, should be in PostScript or another common object-oriented format (such as

*Adobe Illustrator*). In general, illustrations in low-resolution bitmap formats such as GIF, JPEG, and PICT cannot be used.Every attempt will be made to recognize contributors for their assistance. In particular, unless otherwise requested, contributed entries will prominently feature the phrase "This entry contributed by

*contributor name*." A comprehensive tabulation of all recent contributors is maintained on the List of Contributors page. **Q:**I've found a typo/error/bug in*MathWorld.*How can I report it?-
**A:**To report typographical errors, use the convenient web form. Bug reports, great and small, are especially appreciated, and corrections usually appear within a few days.The 2nd edition of Eric Weisstein's book

*CRC Concise Encyclopedia of Mathematics*was typeset by CRC Press and not by the author. As a result, typographical errors that occur only in the printed*CRC Concise Encyclopedia of Mathematics, 2nd ed.*and not on the*MathWorld*website should not be reported to the author. **Q:**Why do I have problems displaying/printing LiveGraphics3D applets?-
**A:**If you are having difficulty viewing LiveGraphics3D applets, your browser and/or Java settings may not be configured properly, or your browser's cache may be garbled. First, try exiting and restarting your browser. If this does not work, try turning Java off, clearing your cache, turning Java back on, and reloading the page.If this still does not work, try upgrading to the newest browser/Java combination available to you. On a Macintosh running pre-Mac OS X, you may also need to allocate more memory to your browser. Note that if you are behind a firewall, your browser's proxy settings might also be configured incorrectly. As a last resort, consult your system administrator.

The images depicted in LiveGraphics3D applets can be printed directly from most web browsers (e.g., Netscape 4.6 under Mac OS, Netscape 4.6 under Linux RedHat 6.0). However, under some operating system/browser/Java combinations, a blank space is obtained when printing where the image should be. If you experience this problem, turn off Java in your browser's Preferences settings and SHIFT-Reload the page. This will bring up the pages with static GIF images instead of applets, and these should print fine. Note that the presence of embedded GIFs within applet tags also allows non-Java-capable browsers to view pages without missing "live" images.

Please see the LiveGraphics3D Homepage or

*MathWorld*'s LiveGraphics3D description page for additional information. **Q:**Do you have an index of mathematical symbols?-
**A:**There is currently no comprehensive index to mathematical symbols used in*MathWorld.*In most cases, a fairly detailed explanation of the symbols used is given for each individual entry. Work is currently underway to create a summary of all symbols, but it will likely not be ready anytime soon.In the meantime, you may find the guide to mathematical notations from the Wolfram Research

*Mathematical Functions*of use. **Q:**Do you have a pronunciation guide?**A:**No, but it would be good to add.**Q:**How does*MathWorld*handle character entities, accents, and international characters?-
**A:***MathWorld*uses characters that are defined in the Latin-1 character set DTD (i.e., DTD/xhtml-lat1.ent) together with a select set of Latin Extended A and part of B set (Unicode range 01; see the Unicode PDF chart Latin Extended-A Range: 0100-017F) including for example, the Hungarian lower case o with double acute (ő = ő). Whereever possible, character entities are specified using symbolic entity names (e.g., é = é) instead of numeric ones (e.g., é = é). In cases where character entities are not used, either the closest equivalent Latin character (stripped of accents) or a GIF image is used. Suggestions for additional characters to display as entities are welcome. **Q:**How does*MathWorld*handle stylesheets (css)**A:***MathWorld*makes minimal use of stylesheets in order to assure compatibility with legacy generation-3.x and 4.x browsers. Doing so is a convenience to the author and allows more streamlined page maintenance and updating. Font, margin, named anchor navigation, and styling markup may therefore appear suboptimal to users of old browsers, but should be readable nonetheless.**Q:**What is the history of*MathWorld*?-
**A:***MathWorld*began life more than 19 years ago. The earliest incarnation of*MathWorld*was a document written in an early version of Microsoft Word on a Macintosh Plus. This document had reached about two hundred pages by the time the author started graduate school in 1990.The author began cross-referencing entries, anticipating that the entire document might someday be converted to hypertext. This hope/dream was realized beginning in 1995, when the internet explosion was in full swing and the author posted the encyclopedia to a personal web site at the California Institute of Technology as part of his web site

*Eric's Treasure Troves of Science*.From July 1996 to June 1999, the author continued to develop and improve the encyclopedia in his spare time while working as a research scientist at the University of Virginia. During this time, the encyclopedia was initially hosted in the author's personal directory in the Department of Astronomy's web server.

Starting in June 1999, the author accepted a position at Wolfram Research, Inc. He began devising a subject-based classification scheme for all entries in the encyclopedia and started the arduous task of subject-classifying each entry in the encyclopedia. It took several months to complete this task for all 10,000+ entries, but it was complete by early November 1999. Work on a new interface and graphical design had been proceeding in parallel, and

*MathWorld*was unveiled in its new form in December 1999.In late 2000, portions of the author's

*Treasure Troves*sites were moved to a new home and renamed*Eric Weisstein's World of Science*. The remaining*Treasure Troves*are still under development and accessible at www.ericweisstein.com/encyclopedias/.In March 2000, CRC Press sued author Eric Weisstein and his employer Wolfram Research and forced

*MathWorld*to be temporarily removed from the internet as a free public resource. The lawsuit was settled in late 2001 and on November 6, 2001,*MathWorld*returned to the internet.In 2008, CRC Press, Eric Weisstein, and Wolfram Research reached an agreement for a new print edition of

*MathWorld*. Work is currently underway to complete the preparation of what will be a 3-volume, 4300-page third edition, whose publication is expected in early 2009. **Q:**When was page*X*last modified?**A:**The pages on*MathWorld*are constantly undergoing revision and extension. A list of new and modified entries is available and kept up-to-date. In addition, the metadata associated with each page uses the Dublin Core standard (in particular, the DC.Date.Created and DC.Date.Modified meta tags) to indicate creation and modification dates. However, this information is is available only from late 1999 onwards.**A:**Yes. With the exception of contributed entries, the entire contents of*MathWorld*have been written over the last two decades by internet encyclopedist Eric Weisstein, with generous assistance from many people in the mathematics and internet communities. Contributions are most welcome. Please see the Become a Contributor page. A discussion of the*MathWorld*project can be found on the about*MathWorld*page.**Q:**Why do pages not print out properly?-
**A:**There is currently no way to suppress the sidebar when printing. If additional resources become available, it's on our list of useful things to do.If you are having problems with parts of a page being cut off when you print, note that

*MathWorld*is formatted to have the maximum allowable width for printing to US letter paper (8.5 inches), corresponding to about 800 pixels. Since A4 paper is slightly narrower, you will have to specify an appropriate reduction in your printer driver in order to avoid cutting off the right-hand side of some text.A good rule of thumb is: if you're having trouble printing, it is your browser's fault. A table of known browser printing issues is given below.

While the current formatting of

*MathWorld*pages has been verified to allow printing to a laser printer when spooled from common operating systems and browsers, your performance may vary depending on your printer, browser, drivers, and preference settings. You may need to consult your printer manual and/or local print guru to obtain good results for your particular setup. **Q:**Who sponsors this site?**A:***MathWorld*is sponsored as a public service by Wolfram Research, Inc. Wolfram Research is the world's leading technical software company and maker of the award-winning technical computing system Mathematica, without which this website could not have been created. Additional information is available about the company and its founder Stephen Wolfram.**Q:**What is the Resource Library?**A:**The Resource Library is the portion of the Wolfram Research website that is devoted to documenting the capabilities of Mathematica and providing information resources that are useful to Mathematica users. The Resource Library contains the Mathematica Documentation Center, as well as general information resources including*MathWorld*and Wolfram Research's*Mathematical Functions*.**Q:**Is the material on*MathWorld*copyrighted?-
**A:**Yes. Although science and mathematics are free to all, these pages represent a considerable amount of labor on the part of the author and are copyrighted. Readers are encouraged to use the contents of these pages for education and enjoyment, but these pages may not be copied, mirrored, or reproduced in bulk without permission of the author. Reproduction for commercial purposes is not permitted, nor is use of robots to create archival copies. Note that this site uses a robots.txt file, which should be honored. If you would like a mathematics encyclopedia you can hold in your own two hands, please consider buying the author's hardcover encyclopedia of mathematics, which contain material similar to that found on this site.In general, honoring copyright statements on the internet will encourage the development of high-quality sites and minimize the clutter of web advertising. Sadly, not everyone abides by copyright symbols (©). Furthermore, some versions of Internet Explorer completely ignore the robots.txt file. As a result, unauthorized attempts at bulk downloading of material will be met by blocking of violators together with the subnets from which they originate.

**Q:**Is the material on*MathWorld*available in formats other than HTML?**A:**No. These pages are intended to be used for reference only and are not available as source documents.**Q:**Why do I get "Access Denied to IP Address xxx.xxx.xxx.xxx"?-
**A:**Your client, subnet, proxy, or cache server has been identified as a source of an extremely large number of hits over a short period of time, possibly resulting from robot activity. Large numbers of requests may represent unauthorized bulk downloading of copyrighted material from these pages.You may want to try disabling any proxy server you are using, since excessive requests from the proxy can lead to its blocking, thus affecting all proxy clients. There is nothing we can do about this since we do not have the time to investigate individual events resulting in bulk downloads. A single user's actions can lead to blocking of an entire proxy and/or subnet, so please be considerate of the author of this site and of your colleagues, so they too can enjoy it.

**Q:**Why do I get "Access Denied to Browser Agent xxx"?-
**A:**Your web browser was found on a list of agents that are barred from accessing this site. Browser agents are blocked when they (1) fail to identify themselves, (2) are known spiders or robots which in the past have been responsible for downloading large numbers of copyrighted pages from this site, or (3) are e-mail siphons that gather e-mail addresses for the purpose of spamming.Note that some "content filtering" programs (

*AtGuard*, in particular) prevent your browser from properly identifying itself and can be responsible for the problem. **Q:**Can I get my own copy of*MathWorld*?**A:**Portions of*Eric Weisstein's World of Mathematics*have been published in hardcover form under the title*CRC Concise Encyclopedia of Mathematics*. The print edition is no longer in stock, but a new third edition prepared by the author is currently in preparation and will be published by CRC Press in early 2009.**Q:**May I host a mirror site or create a personal mirror?**A:**No. The material on this site is updated frequently, and so any mirror would rapidly become out-of-date. Furthermore, mirroring without the permission of the copyright holder is considered copyright violation. If you want to own a mathematical encyclopedia, please consider purchasing the author's hardcover edition, expected to be available in early 2009.**Q:**May I use material from*MathWorld*in my report?**A:**Yes, providing you follow conventional citation standards. Mathematics is free to all, and most mathematical results and theorems cannot be patented or copyrighted. However, the collection and presentation of mathematical results is protected by copyright laws just as are the collection of words in a novel or play and the collection of computer commands in a software package.**Q:**How should I cite material from*MathWorld*?-
**A:**If you excerpt text or graphics from this site for inclusion in a written or online report, you should follow normal protocols for proper citation. An example citation for this site would consist of something like the following:Weisstein, Eric W. "Fibonacci Numbers." From

Other reproduction of material on this site for publication or redistribution is governed by applicable copyright restrictions. For additional questions or for permission to reproduce material for commercial purposes, please send your request via the web form.*MathWorld*--A Wolfram Web Resource.`http://mathworld.wolfram.com/FibonacciNumber.html` **Q:**May I make hyperlinks into*MathWorld*?**A:**Absolutely. Feel free to make hyperlinks into entries in*MathWorld*or to the*MathWorld*top page.**Q:**I need to know more about or have a homework assignment on*X.*Can you help?-
**A:**Yes and no. The author regrettably does not have time to answer specific questions asking for additional information. This includes requests for further references, the solution of problems, the construction or description of algorithms, or the writing of a paper for you. However, in many cases you will be able to find the information you need by browsing and searching the thousands of pages of material already on this site. Contributions and suggestions for additional material to include are also welcome.While suggestions about material that could be added are welcome, blanket requests ("Can you tell me more about matrices?") or requests that require substantial research ("Can you tell me why the symbol

*m*is used for slope?") will likely go unanswered due to the author's limited time. In particular, please note that any messages containing phrases resembling "Please respond as quickly as possible" are almost certain to go unanswered.While

*MathWorld*'s maintainers unfortunately are unable to answer specific mathematics questions, a number of additional resources on the internet may be able to assist you. In particular, The Math Forum @ Drexel offers Ask Dr. Math, an ask-an-expert service for math students with specific questions about mathematics. More information about "Ask Dr. Math" may be found at the following URLs:http://mathforum.org/dr.math/

"Teacher2Teacher" is another Math Forum service specifically intended for questions about the teaching of mathematics. The T2T website is located at

http://mathforum.org/dr.math/ask.htmlhttp://mathforum.org/t2t/

**Q:**Why couldn't I find*X*in*MathWorld*?-
**A:**If you were unable to find specific information you were seeking, there are two possibilities: (1) it is there but you did not find it, or (2) it is not there to find. Try using several different techniques to locate information--*i.e.*, use the subject tree, use the alphabetical index, and do a full-text search. If you still cannot find what you are seeking, it is probably not yet contained in*MathWorld.*If this is the case, try looking up one of the references given at the end of a related article.If you feel the information you are seeking should be added to

*MathWorld*, please consider helping make this happen by becoming a contributor. **Q:**Can I hire you as a consultant on mathematics?**A:**Wolfram Research maintains a list of people who consult on mathematical topics, particularly those involving the use of Mathematica. Please see this page for additional information. The maintainers of*MathWorld*do not act as consultants.**Q:**Can you suggest student projects based on*MathWorld*?-
**A:**There are many interesting unsolved problems in mathematics that could be investigated as part of a student project. As a starting point, you may wish to visit the page on unsolved problems, which gives a few examples and also gives many pointers to internet websites and published books dealing with problems in mathematics, or the alphabetical list of unsolved problems on this site. Of course, many individual entries in*MathWorld*contain material that could be expanded and generalized by the enterprising student.You may also be interested in

*MathWorld*'s pages about mathematics contests and problems involving monetary prizes. **Q:**Do you provide on-line course material, study guides, lesson plans, etc.?**A:**No, not at this time.**Q:**Can you suggest books, classes, or colleges that will help prepare me for a career in mathematics?**A:**While we certainly encourage*MathWorld*readers to pursue mathematics as a career, decisions about career preparation and courses of study are best made with the help of your guidance counselor and teachers. You may also find it helpful to consult books on mathematics in general, mathematical research, or mathematics teaching.**Q:**I would like a book copy of a journal article cited on*MathWorld*. Can you provide one?**A:**No. However, university libraries should carry many of the books and journals cited in*MathWorld*. In addition, most academic institutions have access to older and more obscure journals through interlibrary loan. With the exception of a small number of incomplete references currently being researched, the citations given in*MathWorld*are complete and use a system of slightly modified standard journal abbreviations.**Q:**Can you provide information on how to publish a new mathematical result?**A:**No.**Q:**Is*MathWorld*available in languages other than English?**A:**Unfortunately, the task of translating the entire site is too large to be undertaken at this time. The contents of*MathWorld*are the equivalent of thousands of printed pages, and so would require a vast effort to translate. Such a task would also be made more difficult by the technical nature of the material.Although the

*MathWorld*team has received requests for translations into French, German, Hebrew, Italian, Persian, Portuguese, Russian, and Spanish, at the moment there are no plans for creating them.