visad.math
Class FFT

java.lang.Object
  visad.math.FFT

public class FFT
extends java.lang.Object

FFT is the VisAD class for Fourier Transforms, using the Fast Fourier Transform when the domain length is a power of two.

Constructor Summary

FFT()

Method Summary

static FlatField	backwardFT(Data[] datums) invoke in SpreadSheet by: link(visad.math.FFT.forwardFT(A1))
static double[][]	FFT1D(double[][] x, boolean forward) compute 1-D Fast Fourier Transform
static float[][]	FFT1D(float[][] x, boolean forward) compute 1-D Fast Fourier Transform
static FlatField	forwardFT(Data[] datums) invoke in SpreadSheet by: link(visad.math.FFT.forwardFT(A1))
static FlatField	fourierTransform(Field field, boolean forward) compute Fourier Transform of field
static FlatField	fourierTransform(Field field, boolean forward, FunctionType ftype, GriddedSet domain_set, CoordinateSystem range_coord_sys, Set[] range_sets, Unit[] units) compute Fourier Transform of field; use ftype, domain_set, range_coord_sys, range_sets and units to construct return FlatField - if null, use values from field where appropriate;
static double[][]	FT1D(double[][] x, boolean forward) compute 1-D Fourier Transform, using FFT if domain length is a power of two
static float[][]	FT1D(float[][] x, boolean forward) compute 1-D Fourier Transform, using FFT if domain length is a power of two
static double[][]	FT2D(int rows, int cols, double[][] x, boolean forward) compute 2-D Fourier Transform, calling 1-D FT twice
static float[][]	FT2D(int rows, int cols, float[][] x, boolean forward) compute 2-D Fourier Transform, calling 1-D FT twice; input and output data to this and following static methods are organized: float[2][domain_length] or double[2][domain_length] where the 2 index is over real and imaginary parts
static void	main(java.lang.String[] args) test Fourier Transform methods

Methods inherited from class java.lang.Object

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

Constructor Detail

FFT

public FFT()

Method Detail

forwardFT

public static FlatField forwardFT(Data[] datums)

invoke in SpreadSheet by: link(visad.math.FFT.forwardFT(A1))

backwardFT

public static FlatField backwardFT(Data[] datums)

invoke in SpreadSheet by: link(visad.math.FFT.forwardFT(A1))

fourierTransform

public static FlatField fourierTransform(Field field,
                                         boolean forward)
                                  throws VisADException,
                                         java.rmi.RemoteException

compute Fourier Transform of field

Throws:

VisADException

java.rmi.RemoteException

fourierTransform

public static FlatField fourierTransform(Field field,
                                         boolean forward,
                                         FunctionType ftype,
                                         GriddedSet domain_set,
                                         CoordinateSystem range_coord_sys,
                                         Set[] range_sets,
                                         Unit[] units)
                                  throws VisADException,
                                         java.rmi.RemoteException

compute Fourier Transform of field; use ftype, domain_set, range_coord_sys, range_sets and units to construct return FlatField - if null, use values from field where appropriate;

Throws:

VisADException

java.rmi.RemoteException

FT2D

public static float[][] FT2D(int rows,
                             int cols,
                             float[][] x,
                             boolean forward)
                      throws VisADException

compute 2-D Fourier Transform, calling 1-D FT twice; input and output data to this and following static methods are organized: float[2][domain_length] or double[2][domain_length] where the 2 index is over real and imaginary parts

Throws:

VisADException

FT2D

public static double[][] FT2D(int rows,
                              int cols,
                              double[][] x,
                              boolean forward)
                       throws VisADException

compute 2-D Fourier Transform, calling 1-D FT twice

Throws:

VisADException

FT1D

public static float[][] FT1D(float[][] x,
                             boolean forward)
                      throws VisADException

compute 1-D Fourier Transform, using FFT if domain length is a power of two

Throws:

VisADException

FFT1D

public static float[][] FFT1D(float[][] x,
                              boolean forward)
                       throws VisADException

compute 1-D Fast Fourier Transform

Throws:

VisADException

FT1D

public static double[][] FT1D(double[][] x,
                              boolean forward)
                       throws VisADException

compute 1-D Fourier Transform, using FFT if domain length is a power of two

Throws:

VisADException

FFT1D

public static double[][] FFT1D(double[][] x,
                               boolean forward)
                        throws VisADException

compute 1-D Fast Fourier Transform

Throws:

VisADException

main

public static void main(java.lang.String[] args)
                 throws VisADException

test Fourier Transform methods

Throws:

VisADException