## Math Websites

For the discussion of math. Duh.

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masher
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### Re: mathurl - a LaTeX thingy

antonfire wrote:Also, for embedding, these fora actually have the "imath" and "math" tags now.

Code: Select all

$\zeta(s) = \sum_{n=1}^{\infty} \frac{1}{n^s}$
$\zeta(s) = \sum_{n=1}^{\infty} \frac{1}{n^s}$

that don't work for me on subsilver...

antonfire
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### Re: mathurl - a LaTeX thingy

Yeah, that's actually what pushed me to switch over to prosilver. I like my math pretty.
Jerry Bona wrote:The Axiom of Choice is obviously true; the Well Ordering Principle is obviously false; and who can tell about Zorn's Lemma?

Torn Apart By Dingos
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### Re: mathurl - a LaTeX thingy

Thanks, this is great!

antonfire
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### Re: mathurl - a LaTeX thingy

There's also a very neat little hack that embeds image data directly in the HTML using the "data:" URI here. This doesn't work in IE (people using IE will see a broken image, I guess), but it does work on these fora, using an "img" tag (I had to add two slashes to the URI). It looks ugly in the code, but no outside hosting required, so even if that service ever goes down, your math stays up.

The way the code is right now, I presume it makes images with a white background, which is kind of annoying. It's probably not terribly hard to modify it to make it use an alpha layer, though.
Jerry Bona wrote:The Axiom of Choice is obviously true; the Well Ordering Principle is obviously false; and who can tell about Zorn's Lemma?

the tree
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### Re: mathurl - a LaTeX thingy

jtin wrote:I got tired of trying to type math to peole in IM, and made http://mathurl.com/.
You are amazing. Have some ice cream.

antonfire
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### Re: mathurl - a LaTeX thingy

Okay, you only need to add '-bg Transparent' to the dvipng command in the Ruby script to get it to have a transparent background. I think. I haven't tested it. The antialiasing is messed up for me but I think that's just because I have an older version of dvipng (version 1.5), and it's hardly noticeable on a light background anyway. (By the way, the antialiasing is messed up on mathurl.com as well.)

Anyway, I wrote up a bash script based on the idea above which will turn latex code into the bbcode with an image. This requires latex, dvipng, and openssl.

Code: Select all

#!/bin/bashlatex -halt-on-error -output-directory /tmp \   '\documentclass[12pt]{article}' \   '\pagestyle{empty}' \   '\begin{document}' \   '$' \ "1" \ '$' \   '\end{document}' > /dev/nulldvipng -gamma 2 -z 9 -T tight -bg Transparent -o /tmp/article.png /tmp/article.dvi > /dev/nullecho -n '[img]'echo -n 'data://image/png;base64,'openssl enc -A -a < /tmp/article.pngecho -n '[/img]'rm -f /tmp/article.aux /tmp/article.log /tmp/article.dvi /tmp/article.png

Code: Select all

 > latex2bbcode '0=e^{i\pi}+1'[img]data://image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAEwAAAARCAMAAABAWbowAAAANlBMVEX///8ZGRkJCQkxMTEkJCSQkJAAAAAEBASpqakBAQEQEBDExMRkZGTh4eFRUVF5eXlAQED///8pVmCYAAAAAXRSTlMAQObYZgAAANRJREFUOMvNkt0OwiAMhTuhUn4KvP/TWsAoy8bA6IW9WAhrvp4eDsBieYbflfLwl8Upizgnla8bc0pxZkhgB8kHGKI4bJUVxF03kxZiaQXd32F3jKEiLMnHzOy9MYLPsBu6k4nll7+XowvjTCCKCRt60ATmGoYNNjRDyTKyoj+RPoH5/Kqn1CgusRq83KfKrM5ZHd+6znPd0AajBovnLLRXmToog3txw1C9ofea1LWsw3QSr8woi7UlLMNYMygah5VrNCYwzJtt9g276yxaW/PbOkTvAez4CDOxjqqXAAAAAElFTkSuQmCC[/img]

It's fairly easy to change it to make it spit out html, or just the URI, or whatever.

Obviously, this isn't appropriate for IM conversations (the URIs are huge), but it might be better for forums without TeX support, since all the data is there, rather than on some other server.
Jerry Bona wrote:The Axiom of Choice is obviously true; the Well Ordering Principle is obviously false; and who can tell about Zorn's Lemma?

Fafnir43
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### Re: mathurl - a LaTeX thingy

Holy awesome, Batman! Posting about it in the Maths Sites thread now.
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Fafnir43
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### Re: Math Websites

For when you need to use LaTeX in chat conversation or email with someone who doesn't speak the language: http://mathurl.com/. Enter in the LaTeX, get a tinyurl-style address with the output. Brilliant!
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Torn Apart By Dingos
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### Re: mathurl - a LaTeX thingy

There's an online data:url script here: http://software.hixie.ch/utilities/cgi/data/data
I tried it out and it does transparency too!

gmalivuk
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### Re: mathurl - a LaTeX thingy

masher wrote:
antonfire wrote:Also, for embedding, these fora actually have the "imath" and "math" tags now.

Code: Select all

$\zeta(s) = \sum_{n=1}^{\infty} \frac{1}{n^s}$
$\zeta(s) = \sum_{n=1}^{\infty} \frac{1}{n^s}$

that don't work for me on subsilver...

Because subsilver is no longer really supported, this and subsequent additions are probably not going to work right with it. You should switch to prosilver or prosilver_left if you really can't stand having the user information on the right side of your posts.

Because while all the resources just mentioned, the math and imath tags are still about the most convenient things for forum users to put into their posts, even if they're slightly less convenient for everyone else to read.
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jtin
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### Re: mathurl - a LaTeX thingy

antonfire wrote:There's also a very neat little hack that embeds image data directly in the HTML using the "data:" URI here. This doesn't work in IE (people using IE will see a broken image, I guess), but it does work on these fora, using an "img" tag (I had to add two slashes to the URI). It looks ugly in the code, but no outside hosting required, so even if that service ever goes down, your math stays up.

That's a neat hack!

Thanks antonfire. Will see if I can add this, too...

EDIT: equations on the main page are now rendered with src="data:..." unless user-agent matches MSIE. So you should be able to copy image location to use this method of embedding.

errrr
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### Re: mathurl - a LaTeX thingy

jtin wrote:(Unfortunately LaTeX doesn't contain a symbol for "girl"...)

http://mathurl.com/?5ptk2v
*smiles*

There's also \Womanface in marvosym, but apparently you don't have that package installed.
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existential_elevator
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### Re: Math Websites

http://futuramamath.com/ - does what it says on the tin
http://music.princeton.edu/~dmitri/ - something slightly off the wall linking music and maths

Alpha Omicron
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### Re: Math Websites

Is there anyway to get newlines on mathurl.com? It seems to parse out \\s for me.
Here is a link to a page which leverages aggregation of my tweetbook social blogomedia.

Torn Apart By Dingos
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### Re: Math Websites

Alpha Omicron wrote:Is there anyway to get newlines on mathurl.com? It seems to parse out \\s for me.
You're probably in math mode, where you can't use newlines.

http://mathurl.com/?5cpll8

HenryS
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### Re: Math Websites

Self links, but seem like the kinds of things people here might be interested in:

Note To Self
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### Re: Math Websites

My Maths teacher started this one after leaving for Austrailia shortly after our GCSE's. It's a pretty good site for GCSE and A-Level UK qualifications, though I don't think it will help much more beyond that.

http://www.mrbartonmaths.com
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doishmere
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### Re: Math Websites

http://www.projecteuler.net

Its an ever growing list of mathematical programming challenges. The problems start off easy, such as calculating the sum of the multiples of 3 and 5 through 1000, then get increasingly difficult, such as least-path-sum problems and solving diophantine equations.

This isn't a strictly mathematical website, but its a very good exercise for those who enjoy math and know how to program, or for those who enjoy programing and know math. You'll certainly learn quite a bit about both, but I wouldn't necessarily suggest it to those who are unfamiliar with programming.

This I also find it to be a very good tool when trying to learn a new language; since the first few problems are easy to understand, you can concentrate on how to properly program the problems. Once you get familiar with the language, you're prepared to try to tackle some of the harder problems.

thornahawk
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### Re: Math Websites

Seein' that nobody's posted these yet (from a cursory read, that is; never checked hyperlinks):

http://numbers.computation.free.fr/Cons ... tants.html

http://oldweb.cecm.sfu.ca/projects/ISC/ISCmain.html

http://www.specialfunctions.com/

and last but not the least

http://fooplot.com/

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NathanielJ
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### Re: Math Websites

For people who like Conway's Game of Life, I put together http://www.conwaylife.com. In particular, the LifeWiki could use some more editors if you know a thing or two about the game
Homepage: http://www.njohnston.ca
Conway's Game of Life: http://www.conwaylife.com

Alpha Omicron
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### Re: Math Websites

NathanielJ wrote:For people who like Conway's Game of Life, I put together http://www.conwaylife.com. In particular, the LifeWiki could use some more editors if you know a thing or two about the game

Wow, awesome! I'll stick to Life32 and MCell for my application needs, but that Wiki looks really cool.
Here is a link to a page which leverages aggregation of my tweetbook social blogomedia.

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### Re: Math Websites

What about people that went to college for music and didn't take any math classes. Someone that always had an easy go at math class in school, but doesn't remember a lick of it after 10 years. How would someone like that start learning again? I'm thinking they should start at Algebra and work their way up, but what's the best way to do that? Are there old books on-line (this certain individual lives in Korea and doesn't have access to used book stores)?

Thanks!

Yakk
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### Re: Math Websites

One of the painful things about our time is that those who feel certainty are stupid, and those with any imagination and understanding are filled with doubt and indecision - BR

Last edited by JHVH on Fri Oct 23, 4004 BCE 6:17 pm, edited 6 times in total.

t0rajir0u
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### Re: Math Websites

jaimeastorga2000
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### Re: Math Websites

Here are a few good websites that didn't look like they were posted yet. They are mostly low level stuff, but could be useful to someone who is just starting out.

Trig Without Tears
Allow me to quote a review of this site I have posted elsewhere on the web:
Trig without tears is an awesome site in which some guy explains trigonometry, from the basic functions of sine and cosine to the double and half angle identities. The interesting part is that the author, who believes it is wrong to use memorization as a substitute for thinking and disagrees with the memorization-based approach to identities regularly found in school, instead teaches you how to develop the identities in a way that is easy to follow and remember. I wish I had read this when I was taking pre-calculus in high school.

Karl's Calculus Tutor
Calculus Notes, kinda like the Pauls Online Notes website.

Tutorials For The Calculus Phobe
Calculus Tutorials done in Flash. Well made.
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Kippen
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### Re: Math Websites

For whoever has used the wolfram integrator:
http://www23.wolframalpha.com/
It integrates, shows steps, and does so much more. And, it's free!

Try putting in things like:
int 2x^2 dx
int sin(x^2) dx
int x^y^z dz
sum sum from 2 to infinity 1/n!
FT x^2
23 in base 12

duncanMKZ
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### Re: Math Websites

On a lighter note, I've just started a comedy website called The Daily Week, which has the odd math/science article. Here's the first few paragraphs of a recent example. Hope you enjoy it.

Mathematicians celebrate baffling new proof

Mathematicans around the world were celebrating today, after the announcement that Glimpi's Conjecture had been proved by Edward Chen and Elias Gruenwald at MIT. The 29-year-old Chen said, "We are delighted. Glimpi's Conjecture is literally the Holy Grail of numeric set lassitude mathematics." Gruenwald laughed as he added "And of non-polychromic mathematics in general!"

Reaction from mathematicians worldwide was swift. "Whatever Glimpi's Conjecture is, it sounds like these young men have solved it," said Roger Plapper, from Britain's Royal Society of Sums. "This breakthrough is tremendously, tremendously exciting. We are living in historic times." ...

duncanMKZ
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### Re: Math Websites

NathanielJ wrote:For people who like Conway's Game of Life, I put together http://www.conwaylife.com. In particular, the LifeWiki could use some more editors if you know a thing or two about the game

Fantastic! Thanks for this. I love Conway's Life!

Duncan

osj1961
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### Re: Math Websites

A site I really love is http://www.cut-the-knot.org/content.shtml. It covers a lot of nice math and
has interactive applets that let you play with the ideas.

Another great site for when those inevitable historical questions come up is
http://www-groups.dcs.st-and.ac.uk/~history/ the MacTutor History of Mathematics archive.
-J

Outchanter
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### Re: Math Websites

And now, in the tradition of Stack Overflow:

http://mathoverflow.net/

...the Internet is awesome.
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Tyr_oathkeeper
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### Re: Math Websites

http://betterexplained.com
Very good, intuitive explanations.

Random832
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### Re: Math Websites

Code: Select all

javascript:var s=prompt("Paste the URL").split('=');s[1]=escape(unescape(s[1]));prompt("Here you go",s.join('='));void(0)

A bookmarklet to convert Wolfram Alpha urls into a format that will work on the forum, since []{} need to be escaped to work with bbcode.

(It's a more general problem, but wolfram alpha is the only site I've seen people run into with this, so I posted here - I also only set it up to handle a single url parameter [as with wolfram alpha urls])

BlackSails
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### Re: Math Websites

http://calculuspowerup.com/

This has a whole bunch of stuff, including pdf textbooks (old ones)

MathChief
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### Re: Math Websites

A very nice site, math riddles, some are algorithm problems

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tweetie
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### Re: Math Websites

A very nice site with a few math games (sudoku, kakuro ,jigsawdoku.. ) and other math puzzle releated games: http://mypuzzle.org/

Oolong
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### Re: Math Websites

I've got a page about trigonometry at http://oolong.co.uk/trig.htm

I'm experimenting with expandable sections (to include some *slightly* more advanced stuff without scaring off newbies) and an interactive diagram (I love interactive diagrams, but I'm still not sure about including Java or non-IE JavaScript without warning, so by default this diagram is still just an image)... so feedback on those bits is especially welcome.

Blarnay
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### Re: Math Websites

Salman Khan (Sal) founded the Khan Academy with the goal of using technology to educate the world
Sal received his MBA from Harvard Business School. He also holds a Masters in electrical engineering and computer science, a BS in electrical engineering and computer science, and a BS in mathematics from the Massachusetts Institute of Technology.

He's got youtube videos on everything from basic arithmetic to calculus and linear algebra. This man is my hero.

wigglyworm91
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### Re: Math Websites

Here's ( http://www.mathoverflow.com/ ) a really useful question-and-answer site for concrete, answerable questions. Used a lot -- the latest question was asked 2 minutes ago and it already has 2 answers.

It's actually part of a family of sites:
http://www.stackoverflow.com
http://www.serverfault.com
http://www.superuser.com
http://www.doctype.com
Need more help or clarification? Feel free to PM me.
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aleph_one
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### Re: Math Websites

I recently found The Unapologetic Mathematician, an expository math blog by John Armstrong. It has readable, well-explained, and decently comprehensive expositions on pretty much everything (linear algbebra, category theory, topology, etc...) My only complaint is that the blog format makes it hard to follow a topic, since sometimes a post links to one in another topic for background, which links to another one, and so on, and the reverse order (later things come first) is annoying - does anyone know a convenient way to read it?

rrwoods
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The Khan Academy has an absolutely enormous amount of information on lots of mathematical topics and even some non-mathy ones. Salman Khan is amazing at explaining things, and he's got videos on basic arithmetic, algebra, geometry, linear algebra, calculus, differential equations... chemistry... the french revolution (lolwut)...

Anyone have any success stories or other thoughts to share?
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