marf.math
Class Algorithms.FFT

java.lang.Object
  marf.math.Algorithms.FFT

Enclosing class:

Algorithms

public static final class Algorithms.FFT
extends java.lang.Object

A collection of FFT-related math.

Author:

Stephen Sinclair, Serguei Mokhov

Constructor Summary

Algorithms.FFT()

Method Summary

static void	doFFT(double[] padInputReal, double[] padInputImag, double[] padOutputReal, double[] padOutputImag, int piDirection) FFT algorithm, translated from "Numerical Recipes in C++" that implements the Fast Fourier Transform, which performs a discrete Fourier transform in O(n*log(n)).
static void	doFFT2(ComplexMatrix poInputMatrix, ComplexMatrix poOutputMatrix, int piDirection) Performs 2D FFT; which is merely 1D FFT for every column, and then, 1D FFT of every row of the result.
static void	normalFFT(double[] padSample, double[] padMagnitude) Performs a normal FFT, taking a real input (supposedly an audio sample) and returns the frequency analysis in terms of "magnitude".
static void	normalFFT(double[] padSample, double[] padMagnitude, double[] padPhaseAngle) Performs a normal FFT, taking a real input (supposedly an audio sample) and returns the frequency analysis in terms of "magnitude" and "phase angle".

Methods inherited from class java.lang.Object

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

Constructor Detail

Algorithms.FFT

public Algorithms.FFT()

Method Detail

doFFT

public static final void doFFT(double[] padInputReal,
                               double[] padInputImag,
                               double[] padOutputReal,
                               double[] padOutputImag,
                               int piDirection)
                        throws MathException

FFT algorithm, translated from "Numerical Recipes in C++" that implements the Fast Fourier Transform, which performs a discrete Fourier transform in O(n*log(n)).

Parameters:

padInputReal - InputReal is real part of input array

padInputImag - InputImag is imaginary part of input array

padOutputReal - OutputReal is real part of output array

padOutputImag - OutputImag is imaginary part of output array

piDirection - Direction is 1 for normal FFT, -1 for inverse FFT

Throws:

MathException - if the sizes or direction are wrong

doFFT2

public static final void doFFT2(ComplexMatrix poInputMatrix,
                                ComplexMatrix poOutputMatrix,
                                int piDirection)
                         throws MathException

Performs 2D FFT; which is merely 1D FFT for every column, and then, 1D FFT of every row of the result.

Parameters:

poInputMatrix -

poOutputMatrix -

piDirection -

Throws:

MathException

Since:

0.3.0.6

normalFFT

public static final void normalFFT(double[] padSample,
                                   double[] padMagnitude,
                                   double[] padPhaseAngle)
                            throws MathException

Performs a normal FFT, taking a real input (supposedly an audio sample) and returns the frequency analysis in terms of "magnitude" and "phase angle".

Parameters:

padSample - must be an array of size (2^k)

padMagnitude - must be half the size of "sample"

padPhaseAngle - must be half the size of "sample"

Throws:

MathException

normalFFT

public static final void normalFFT(double[] padSample,
                                   double[] padMagnitude)
                            throws MathException

Performs a normal FFT, taking a real input (supposedly an audio sample) and returns the frequency analysis in terms of "magnitude".

Parameters:

padSample - must be an array of size (2^k)

padMagnitude - must be half the size of "sample"

Throws:

MathException