Respace

April 19, 2016

The two seemingly trivial and unimportant problems of what kind of whitespaces and how to use them are still not solved. Some still use hard-coded tabs in their source code, and because they set tabs to be two spaces wide in their favorite editor, they expect the rest of the planet to have done so. The result is that spacing will break in another person’s editor, and the code will look like it’s been written by a four years old. Also, when tabs and spaces are mixed, and randomly interpreted, the indentation, the general aspect of how the code is presented, is broken.

turbo-napkin

While marking assignments, I encountered a number of such pieces of code. So I decided to fix that with a simple Emacs command.

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Huffman Codes

May 17, 2011

Some time ago, I presented a piece on compressing voxel worlds and I just realized that I discussed different types of variable length codes quite a few times, but that I never took the time to present you the basic method of Huffman coding!

The problem of finding an optimal variable length code is to find an uniquely decodable binary code (that is, a code using only 0 and 1 for which there exists only one way of decoding a message) that encodes each symbol in a number of bits that is proportional to its probability of occurrence. A first strategy was devised by Robert Fano, Huffman’s teacher at one point. The so-called Shannon-Fano code is a top-down approach to solving the problem but it was shown to be suboptimal. The code proposed by David Huffman solves the problem optimally by taking exactly the opposite approach, that is, building the code bottom-up.

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