fft

README

fft

radix-2 fast Fourier transform

Package fft provides a fast discrete Fourier transformation algorithm.

Implemented is the 1-dimensional DFT of complex input data for with input lengths which are powers of 2.

The algorithm is non-recursive and works in-place overwriting the input array.

Before doing the transform on acutal data, allocate an FFT object with t := fft.New(N) where N is the length of the input array. Then multiple calls to t.Transform(x) can be done with different input vectors having the same length.

Documentation

Overview

Package fft provides a fast discrete Fourier transformation algorithm.

Implemented is the 1-dimensional DFT of complex input data for with input lengths which are powers of 2.

The algorithm is non-recursive and works in-place overwriting the input array.

Before doing the transform on acutal data, allocate an FFT object with t := fft.New(N) where N is the length of the input array. Then multiple calls to t.Transform(x) can be done with different input vectors having the same length.

Index

• type FFT
  • func New(N int) (f FFT, err error)
  • func (f FFT) Inverse(x []complex128) []complex128
  • func (f FFT) Transform(x []complex128) []complex128
• type NFFT
  • func Prepare(n uint16) NFFT
  • func (f NFFT) Complex(x []complex128)
  • func (f NFFT) Real2(x, y []float64, out []complex128)

Types

type FFT

type FFT struct {
	N int // Fft length, power of 2.

	E []complex128 // Precomputed roots table, length N.
	// contains filtered or unexported fields
}

func New

func New(N int) (f FFT, err error)

func (FFT) Inverse

func (f FFT) Inverse(x []complex128) []complex128

Inverse is the backwards transform.

func (FFT) Transform

func (f FFT) Transform(x []complex128) []complex128

Forward transform. The forward transform overwrites the input array.

type NFFT

type NFFT struct {
	// contains filtered or unexported fields
}

func Prepare

func Prepare(n uint16) NFFT

func (NFFT) Complex

func (f NFFT) Complex(x []complex128)

func (NFFT) Real2

func (f NFFT) Real2(x, y []float64, out []complex128)