edu.ucla.sspace.fft

Class FastFourierTransform

java.lang.Object

edu.ucla.sspace.fft.FastFourierTransform

public class FastFourierTransform
extends Object

Computes FFT's of DoubleVectors. The physical layout of the mathematical data d[i] in the array data is as follows:

    d[i] = data[i0 + stride*i]

The FFT (D[i]) of real data (d[i]) is complex, but restricted by symmetry:

    D[n-i] = conj(D[i])

Author:

Keith Stevens, Derived from JNT FFT code by Bruce R. Miller bruce.miller@nist.gov, Derived from GSL (Gnu Scientific Library), Contribution of the National Institute of Standards and Technology,

Constructor Summary

Constructors

Constructor and Description
FastFourierTransform()

Method Summary

Methods

Modifier and Type	Method and Description
static void	backtransform(DoubleVector data) Compute the (unnomalized) inverse FFT of data, leaving it in place.
static void	bitreverse(DoubleVector data, int i0, int stride) This is the Gold rader bit-reversal algorithm
static int	checkFactor(int n) Create an FFT for transforming n points of real, double precision data.
static void	transform(DoubleVector data) Compute the Fast Fourier Transform of data leaving the result in data.

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

checkFactor

public static int checkFactor(int n)

Create an FFT for transforming n points of real, double precision data. n must be an integral power of 2.

transform

public static void transform(DoubleVector data)

Compute the Fast Fourier Transform of data leaving the result in data.

backtransform

public static void backtransform(DoubleVector data)

Compute the (unnomalized) inverse FFT of data, leaving it in place. The data must be in the same arrangement as that produced by transform.

bitreverse

public static void bitreverse(DoubleVector data,
              int i0,
              int stride)

This is the Gold rader bit-reversal algorithm