Xah Math Blog Archive 2012-05

Mathematician Robert J Vanderbei https://www.facebook.com/robert.vanderbei made a comment at Geometry: Gallery of Surfaces. He wrote a surface viewer using latest tech WebGL. It's excellent. Check it out at [ http://www.princeton.edu/~rvdb/WebGL/minsurf.html ] . You will need to use a broweser that supports WebGL, such as Google Chrome.

I can never remember what “xor” do. But now i got a easy way to remember it. xor returns true if the values of two sides differ.

See also: Logical Operators, Truth Table, Unicode

update: Math Font, Unicode, Gothic Letters, Double Struck, 𝔄 𝔅 ℭ

updated links: Great software for Tilings, Patterns, Symmetry

Great Software for Plane Geometry

Understanding Public-Key Cryptography for Beginner

bug eyed monster Hop David
BEM - Bug Eyed Monster, by Hop David.

Math Art of Hop David

this tweet is going around:

Dear math, i'm sick and tired of finding your x, just accept the fact that she is gone.

It needs a prelude:

dear girls, i had a fight with my x, but i think she loves me still. help me find x^2+1=5. —Math

3 wonderful articles on cycloids. By mathematician physicist John C. Baez .

It mentioned my site a lot. Thanks John.

William Thurston died. (1946 to 2012). Of skin cancer.

I think i first heard of him thru Jeff Week's book 〈The Shapes of Space〉. [see Reading Notes on “The Shape of Space”] I realized that he's one of the world's top mathematician. Though, his work is beyond my understanding.

anti-calculus toothpaste
Anti-Calculus, but is it anti-derivative?

What Voting Systems are There?

Memories of Kurt Gödel By Rudy Rucker. At http://www.rudyrucker.com/blog/2012/08/01/memories-of-kurt-godel/

what i saw
“what i saw”. Source thepunsultancy.blogspot.com

Discovered a Unicode Character ℇ (EULER CONSTANT)

Discovered a Unicode char

character: ℇ (codepoint 8455, #o20407, #x2107)
old-name: EULERS

This is a bit strange. It's not clear whether it meant the base of the natural logarithm or Euler–Mascheroni constant .

The symbol for the base of the natural logarithm is traditionally (SCRIPT SMALL E), while the symbol for Euler–Mascheroni constant is γ (GREEK SMALL LETTER GAMMA).

The Unicode has name EULER CONSTANT. It's a bit ambiguous, but i suppose it means . However, i tried several Unicode fonts, all of them has the appearance of mirrored 3, none showed it as .

point of views
point of view
sine curve lady

Geometric Dissection in Expandable Table Furniture 📺

Space Groups, Math and Chicks

got a chick from Moscow State University asking me about implementing Space group in Mathematica. Life's been worth living.

Anna, yes, you.

… haven't worked on this since 1998. I did 2D version. The 3D version would be much spectacular, especially with today's computing technologies (For example, dynamic rotation in web browser). Also, going into higher dimension (For example, 4th) would be a wonderful exercise in writing combinatorics programs or exploration into proof systems. Dimension 7 or higher hasn't been solved yet. Fame awaits!

Nice article:

See also: The Problems of Traditional Math Notation .

Fractal Gears

fractal gears clockwork by zy0rg
“clockwork” (2012) by zy0rg

Math Art: Fractal Clockwork

updated: The Problems of Traditional Math Notation

Mandelbrot Set Explained (no complex number needed)

complex number simply explained: Geometric Transformation on the Plane