dctmtx

Parameters

n:

Real scalar integer greater than or equal to 1

Description

This is an Octave function dctmtx(n) returns a Discrete cosine transform matrix of order n-by-n. It is useful for jpeg image compression. D*A is the DCT of the columns of A and D'*A is the inverse DCT of the columns of A (when A is n-by-n).

Examples

1. dctmtx(2) ans = [0.70711 0.70711; 0.70711 -0.70711] 2. dctmtx(3) ans = [5.7735e-01 5.7735e-01 5.7735e-01; 7.0711e-01 4.9996e-17 -7.0711e-01; 4.0825e-01 -8.1650e-01 4.0825e-01]