xal.tools.math

Class DiscreteFourierTransform

java.lang.Object

xal.tools.math.DiscreteFourierTransform

public class DiscreteFourierTransform
extends java.lang.Object

Calculates the discrete fourier transform. While not as efficient as a fast fourier transform, it offers more flexibility. transform(f) = 1/2N * sum( f(t) e^(i pi p k / N) ), k = 0...2N-1, t = kT/2N, freq = 2 pi p / T, p = 0...2N-1

Constructor Summary

Constructors

Constructor and Description
DiscreteFourierTransform(double[] values, double period) Constructor

Method Summary

Modifier and Type	Method and Description
double	getFrequency(int index) get the frequency associated with the frequency index
Complex[]	getSpectrum() get the transform at the specified frequency index
int	getSpectrumCount() get the count of the elements in the transform
double	getTime(int index) get the time for the specified time index
double[]	getValues() get the time based array of values

Methods inherited from class java.lang.Object

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

Constructor Detail

DiscreteFourierTransform

public DiscreteFourierTransform(double[] values,
                                double period)

Constructor

Parameters:

values - is an even number of values evenly spaced over time

period - is the time period

Throws:

java.lang.RuntimeException - if the number of time based elements is not even

Method Detail

getValues

public double[] getValues()

get the time based array of values

getTime

public double getTime(int index)

get the time for the specified time index

getSpectrum

public Complex[] getSpectrum()

get the transform at the specified frequency index

getSpectrumCount

public int getSpectrumCount()

get the count of the elements in the transform

getFrequency

public double getFrequency(int index)

get the frequency associated with the frequency index