Node.js implementation of the Discrete Cosine Transform (version 2 for now).
The discrete cosine transform (DCT) is used widely for signal compression due to its power compaction properties as opposed to the discrete fourier transform.
For a signal of length N the DCT function returns a vector of coefficients of length N, each coefficient representing how closely the signal maps to that cosine function.
The first coefficient represents a flat function. As a result, if the input is all the same value the first coefficient is going to be a non-zero value while all other coefficients should be close to zero.
Various versions of the DCT exist, each one having special properties. For its widespread use this implementation uses the DCT-II with a scaling factor of 2.
var dct = require('dct'),
signal = [1,1,1,1,1];
var coef = dct(signal);
console.log(coef); // [12, 0, 0, 0, 0]
npm run test
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