Category: Mathematica

2D Matrix Decomposition
This demonstrates the polar decomposition of 2D matrices into their angle, scale, and shear components. The polarDecomp algorithm is taken from Shoemake & Duff “Matrix Animation and Polar Decomposition“, 1992.

Defining new format wrappers in Mathematica
One problem I had with the expressiontoC converter is that CForm converts negations of terms into a negation of parenthesized terms.

Converting symbolic Mathematica expressions to C code
I frequently use Mathematica to rearrange or solve symbolic equations to use in C++ programs. While Mathematica is quite powerful for that, it has no facility to hoist common subexpressions into variables.

Adding a keyboard shortcut to Mathematica V7
(updated 20090323 to add the backslashes that disappeared between my blog editor and WordPress) In Mathematica, typing index brackets is clumsy, as one has to type esc[[esc then esc]]esc. I found a way to modify the Edit menu to add a shortcut for this.

Pixelperfect Graphics, Revisited
Mathematica 7 introduces a new Image function that eliminates all the hassle previously necessary to create and export pixelperfect raster images.

Exporting PixelPerfect Graphics in Mathematica
I keep having to figure out how to export pixelperfect raster images from Mathematica, which I use for test images with my software. I found that it’s simpler to use ArrayPlot than Raster now, so I’m documenting this for my future use (and any one else’s).