idct

Syntax

y = idct(x)

y = idct(x,n)

Inputs

x

The transform to be inverted.

Type: double

Dimension: vector | matrix

n

The idct length (default: the input vector length).

Type: integer

Dimension: scalar

Outputs

y

The inverse transform of x.

Example

Demonstrate data compression by inverting a transform after zeroing the final four values.

x = [1, 4, 9, 16, 25, 36, 49, 64];
y = dct(x)
y(5:8) = 0
z = idct(y)

y = [Matrix] 1 x 8
72.12489  -57.98091  12.61729  -6.06109  2.82843  -1.80813  0.89668  -0.45632
y = [Matrix] 1 x 8
72.12489  -57.98091  12.61729  -6.06109  0.00000  0.00000  0.00000  0.00000
z = [Matrix] 1 x 8
0.37521  4.40076  9.95187  15.69950  23.64365  36.21970  51.42766  62.28164

Comments

The idct is applied to a vector input or to each column vector of a matrix input. When n is used, each input vector is either truncated or extended with zeroes to the specified length. idct uses the FFTW library.