Class FFT

java.lang.Object
  extended by 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