jigl.signal.utils
Class FFT

java.lang.Object
  |
  +--jigl.signal.utils.FFT

public class FFT

extends Object

Fast Fourier Transform Class for one-dimension signal. Makes sure that the length of your signal is of power of 2 before applying FFT.

To get the correct shape of the Fourier Transform, you should shift the result signal right by half length.

Field Summary

(package private) static int	MAX_POW Defines maximum length of the signal, which is 2^MAX_POW.
(package private) static int[]	pow2 An array to store the integers of power of 2.

Constructor Summary

FFT()
Default constructor

Method Summary

(package private) static void	bitDump(int d)
(package private) static int	BitReverse(int i, int k)
static ComplexSignal	doFFT(Signal im, boolean forward) Perforn the Fourier transform
static ComplexSignal	forward(Signal im) Perform the Fourier Transform
static ComplexSignal	inverse(Signal im) Perform the Inverse Fourier Transform

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

MAX_POW

static final int MAX_POW

Defines maximum length of the signal, which is 2^MAX_POW.

See Also:

Constant Field Values

pow2

static final int[] pow2

An array to store the integers of power of 2.

Constructor Detail

FFT

public FFT()

Default constructor

Method Detail

BitReverse

static int BitReverse(int i,
                      int k)

bitDump

static void bitDump(int d)

forward

public static ComplexSignal forward(Signal im)

Perform the Fourier Transform

inverse

public static ComplexSignal inverse(Signal im)

Perform the Inverse Fourier Transform

doFFT

public static ComplexSignal doFFT(Signal im,
                                  boolean forward)

Perforn the Fourier transform

Parameters:

forward - true=Fourier, false=Inverse Fourier