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.
One problem I had with the expression-to-C converter is that CForm converts negations of terms into a negation of parenthesized terms.
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.
(updated 2009-03-23 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. Read more…
Mathematica 7 introduces a new Image function that eliminates all the hassle previously necessary to create and export pixel-perfect raster images.
I keep having to figure out how to export pixel-perfect 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).
Read more…