IDCT

Purpose:

Calculates the Unitary Inverse Discrete Cosine Transform.

IDCT(series, n)

series	-	An input series or array.
n	-	Optional. An integer, the transform length. Defaults to length(series).

A series or array.

idct(dct(gcos(100, 1/100, 20)))

returns a 20 Hz cosine wave.

The unitary inverse discrete cosine transform is defines as:

The transform is applied to each column if the input is an array. The IDCT is often used in conjunction with DCT to perform image compression.