(fast-fft) ( seq inverse? -- seq' )

Vocabulary

math.transforms.fft.private

Inputs

seq	an object
inverse?	an object

Outputs

seq'

an object

Definition

USING: kernel math math.constants math.functions sequences
sequences.extras ;

IN: math.transforms.fft.private

:: (fast-fft) ( seq inverse? -- seq' )
    seq length :> N N 1 =
    [ seq ] [
        seq even-indices inverse? (fast-fft)
        seq odd-indices inverse? (fast-fft) inverse? 1 -1 ?
        2pi * N / [ * cis * ] curry map-index!
        [ [ + inverse? [ 2 / ] when ] 2map ]
        [ [ - inverse? [ 2 / ] when ] 2map ] 2bi append
    ] if ; inline recursive