vec_math
Class FastFourierTransform

java.lang.Object
  vec_math.FastFourierTransform

public class FastFourierTransform
extends Object

Does a fast fourier transform following the algorithm presented in Numerical Recipes, p. 507f

Nested Class Summary

static class	FastFourierTransform.RealTest Test the real-value fft.
static class	FastFourierTransform.Test
static class	FastFourierTransform.WhiteNoise

Constructor Summary

FastFourierTransform()

Method Summary

static Complex[]	fft(Complex[] x) Does fft in the complex domain.
static Complex[]	ifft(Complex[] x) Does inverse fft in the complex domain.
static Complex[]	realFft(Double[] real) Does an fft of a real data set by splitting it into a complex array half the size.
static double[]	zeroPad(double[] in) Returns a double array that is zero-padded to both side and has a length that is the closest ceiling power-of-two to the length of the input array.

Methods inherited from class java.lang.Object

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

Constructor Detail

FastFourierTransform

public FastFourierTransform()

Method Detail

fft

public static Complex[] fft(Complex[] x)

Does fft in the complex domain. The input data is conserved and a new complex array is retuyrned. This is not very memory efficient.

Parameters:

x - Complex input data, length must be a power of 2.

Returns:

The Fourier transform of the input data or null input has wrong length.

ifft

public static Complex[] ifft(Complex[] x)

Does inverse fft in the complex domain. The input data is conserved and a new complex array is retuyrned. This is not very memory efficient.

Parameters:

x - Complex input data, length must be a power of 2.

Returns:

The inverse Fourier transform of the input data or null input has wrong length.

realFft

public static Complex[] realFft(Double[] real)

Does an fft of a real data set by splitting it into a complex array half the size.

Returns:

The positive half of the transform an array of n/2+1

zeroPad

public static double[] zeroPad(double[] in)

Returns a double array that is zero-padded to both side and has a length that is the closest ceiling power-of-two to the length of the input array. Uses the System.arraycopy(java.lang.Object, int, java.lang.Object, int, int) method.