fftManager

Class FastFFT

java.lang.Object

fftManager.FastFFT

public class FastFFT
extends java.lang.Object

FFT Wrapper which uses the edu.emory.mathcs.jtransforms.fft transforms library for the actual FFT calculations.
These are simple wrappers to use the transofrms library with standard PAMGUARD transform classes.

Author:

Doug Gillespie

Constructor Summary

Constructors

Constructor and Description
FastFFT()

Method Summary

Methods

Modifier and Type	Method and Description
void	fft(Complex[] x) In place fft of complex data.
void	fft(Complex[][] x) In lace FFT of a 2D complex array.
void	ifft(Complex[] x, int m) Inverse FFT for Complex data.
static int	log2(int num)
static int	nextBinaryExp(int sourceNumber) Finds the next highest binary exponential of the input integer.
Complex[]	rfft(double[] x, Complex[] y, int m) Fast FFT function for real data.

Methods inherited from class java.lang.Object

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

Constructor Detail

FastFFT

public FastFFT()

Method Detail

rfft

public Complex[] rfft(double[] x,
             Complex[] y,
             int m)

Fast FFT function for real data.

Parameters:

x - real data array

y - preallocated Complex array for output data (can be null)

m - log2 of the FFT length (sorry !)

Returns:

Complex FFT data.

fft

public void fft(Complex[] x)

In place fft of complex data.

Parameters:

x - complex array

fft

public void fft(Complex[][] x)

In lace FFT of a 2D complex array. Will use the multithreading abilities of the JTransofrms library.

Parameters:

x -

ifft

public void ifft(Complex[] x,
        int m)

Inverse FFT for Complex data.
I FFT is performed 'in place' so data are overwritten

Parameters:

x - Complex Data

m - log2 of the FFT length (sorry !)

nextBinaryExp

public static int nextBinaryExp(int sourceNumber)

Finds the next highest binary exponential of the input integer. If the input is itself a binary exponential, then the result is itself. E.g. given 7 returns 8, 8 returns 8, 9 returns 16. Notes has limit of 2^100. Matlab calls this function nextpow2; it's also akin to frexp in C.

Parameters:

sourceNumber -

Returns:

The next highest 2^ of the input, unless input is itself a binary exponential.

log2

public static int log2(int num)

Parameters:

FFTlength -

Returns:

log2 of FFTlength, -1 if not natural power of 2