
Discrete Cosine Transform, Type II and IIIThe discrete cosine transform of type III is given by the matrix where a_{k} = sqrt(1/2) for k = 0, and a_{k} = 1 else. The DCT type II is the transpose of type III. The following structured, sparse matrix factorization represents a fast algorithm for a DCT, type III, size 8, and has been automatically generated (even in the presented Latex format) using the package AREP. By transposition we obtain a fast algorithm for the DCT^{(II)}: O.k., you where not looking for math, but hoping to find good code for this (or other) transforms? No problem, get SPIRAL. 