Class FFT

java.lang.Object
  FFT

public class FFT
extends java.lang.Object

class FFT computes the fft of a set of samples passed

Field Summary

static double	ISIP_INV_SQRT2
static double	ISIP_TWOPI

Method Summary

boolean	isPower(int exponent, int base) this method computes exponent = log (base) of order; it returns false if order of the fourier transform requested for is not a power of base.
boolean	srComplex(double[] output, double[] input) This method computes the fourier transform using the split-radix algorithm.
boolean	srfft(double[] output, double[] input) Routine used to compute the real split-radix fft.
boolean	srInit() creates lookup tables for sin and cosine terms.

Methods inherited from class java.lang.Object

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

Field Detail

ISIP_INV_SQRT2

public static final double ISIP_INV_SQRT2

See Also:

Constant Field Values

ISIP_TWOPI

public static final double ISIP_TWOPI

See Also:

Constant Field Values

Method Detail

srInit

public boolean srInit()

creates lookup tables for sin and cosine terms.

Returns:

true

isPower

public boolean isPower(int exponent,
                       int base)

this method computes exponent = log (base) of order; it returns false if order of the fourier transform requested for is not a power of base.

Parameters:

exponent - (output) the required exponent

base - (input) base provided by the user

Returns:

boolean value indicating status

srComplex

public boolean srComplex(double[] output,
                         double[] input)

This method computes the fourier transform using the split-radix algorithm. This code is based on the code by G.A.Sitton of the Rice University. The theory behind the implementation closely follows the description of the split-radix algorithm in: J.G.Proakis, D.G.Manolakis, "Digital Signal Processing - Principles, Algorithms, and Applications" 2nd Edition, Macmillan Publishing Company, New York, pp. 727-730, 1992.

Parameters:

output - (output) output data array length of output array will always be 2*N memory is allocated internally, not by the calling program.

input - (input) input data array length of input array is 2*N memory is allocated by the calling program.

Returns:

boolean indicating status of computation

srfft

public boolean srfft(double[] output,
                     double[] input)

Routine used to compute the real split-radix fft. This code is based on the code by G.A.Sitton of the Rice University. The theory behind the implementation closely follows the description of the split-radix algorithm in: J.G.Proakis, D.G.Manolakis, "Digital Signal Processing - Principles, Algorithms, and Applications" 2nd Edition, Macmillan Publishing Company, New York, pp. 727-730, 1992.

Parameters:

output - (output) output data array length of output array will always be 2*N memory is allocated internally, not by the calling program.

input - (input) input data array length of input array is 2*N memory is allocated by the calling program.

Returns:

boolean indicating status of computation