How to validate a credit card number (click for full pic)

[via:Viralliset Linkit]

Math Overflow, a Questions and Answers site for math problems

Implemented using the platform of Stack Overflow, a Q&A board for programming topics. Beats any old-type forums or wiki sites, they have among other things, an addicting reputation and badge system inspired by Xbox Live.

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In â€œInfectious Disease Modelling Research Progress,â€ eds. J.M. Tchuenche and C. Chiyaka, Nova Science Publishers, Inc. pp. 133-150, 2009.

Wired provides a summary.

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The magic word is *PolarPlot[(1 + 0.9 Cos[8 t]) (1 + 0.1 Cos[24 t]) (0.9 + 0.05 Cos[200 t]) (1 + Sin[t]), {t, -Pi, Pi}*.

[via:saasta.fi]

Mathematicians create videos that help in visualizing four-dimensional objects

The article has a broken link to dimensions-math.org.

[via:Slashdot]