Welcome to Stoney’s Zone
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The Even-more Complete List of Hex Words
I realized that I was being insufficiently lee7, so I added S, T, and Z, converting into 5, 7, and 2. This produced a much longer list, of course.
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The Complete List of Hex Words
While converting some code to 64-bit on Snow Leopard, I discovered that character literals are ints, so I couldn’t use them for 8-byte longs. The alternative is readable hex constants.
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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.
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Mirroring git respositories to DreamHost
Casper Fabricius has a nice shell script for creating new git repositories on DreamHost. Unfortunately, this works only for creating new repositories.
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Defining new format wrappers in Mathematica
One problem I had with the expression-to-C converter is that CForm converts negations of terms into a negation of parenthesized terms.
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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.
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Adding a keyboard shortcut to Mathematica V7
(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.
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Pixel-perfect Graphics, Revisited
Mathematica 7 introduces a new Image function that eliminates all the hassle previously necessary to create and export pixel-perfect raster images.
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What is a sampling test image?
I was asked what the purpose is of the test image in my previous post, and why the alpha was set to 0.01 rather than 0 in alternating pixels.
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Exporting Pixel-Perfect Graphics in Mathematica
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).