signalproc.algorithms

Class FFTPhase

java.lang.Object

signalproc.algorithms.FFTPhase

public class FFTPhase
extends java.lang.Object

Class FFTPhase contains utilities for the computation of phases for the Fast Fourier Transform methods in Triana. It initializes phases, keeps them in Hashtables for later use, and provides them on demand to other programs.

Constructor Summary

Constructors

Constructor and Description
FFTPhase(boolean information) Constructor for FFTPhase sets the verbose flag, to determine whether comments are written to System.out.

Method Summary

Methods

Modifier and Type	Method and Description
void	display3()
double[]	getPhase(int m)
double[]	getPhaseImaginaryParts()
double[]	getPhaseRealParts()
void	makePhase(int nElements) The method makePhase( int nElements) creates a vector of n complex numbers uniformly spaced counter-clockwise around the unit circle.

Methods inherited from class java.lang.Object

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

Constructor Detail

FFTPhase

public FFTPhase(boolean information)

Constructor for FFTPhase sets the verbose flag, to determine whether comments are written to System.out.

Method Detail

getPhaseRealParts

public double[] getPhaseRealParts()

getPhaseImaginaryParts

public double[] getPhaseImaginaryParts()

display3

public void display3()

makePhase

public void makePhase(int nElements)

The method makePhase( int nElements) creates a vector of n complex numbers uniformly spaced counter-clockwise around the unit circle. Used in FFTs, these are suitable for the inverse transform. Direct transforms must use the complex-conjugates.

It stores their real and imaginary parts, respectively, in the vectors of doubles phaseReal[] and phaseImag[]. It only computes phases if there are more than 2 points. If there are 2 or fewer, the phases are trivial and are not needed by the Fourier methods.

The method stores computed phase vectors in static Hashtables and looks for them when it is called another time, so that avoids re-computing phase vectors unnecessarily. It can use stored vectors that contain an integer multiple of nElements elements.

Parameters:

nElements - Number of complex numbers on unit circle.

getPhase

public double[] getPhase(int m)