org.opensourcephysics.analysis
Class FourierSinCosAnalysis

java.lang.Object
  org.opensourcephysics.analysis.FourierSinCosAnalysis

All Implemented Interfaces:

Data

public class FourierSinCosAnalysis
extends java.lang.Object
implements Data

FourierAnalysis adds gutter points to real data before performing a fast Fourier transform. Gutter points increase the number points in order to approximate a nonperiodic function. The FFT output is phase shifted to account for the fact that the FFT basis functions are defined on [0, 2*pi].

Version:

1.0

Author:

W. Christian

Constructor Summary

FourierSinCosAnalysis()

Method Summary

double[]	doAnalysis(double[] x, double[] y, int gutter) Fourier analyzes the given data y[] after adding gutter points at the start and end of the z[] array.
java.util.ArrayList	getComplexDatasets() Complexdatasets are not available.
double[][]	getData2D() Gets the frequencies, power, cos, and sin coefficients.
double[][][]	getData3D() 3D data is not available.
java.util.ArrayList	getDatasets() Gets the datasets that contain the result of the last Fourier analysis.
double[]	getNaturalFreq() Gets the frequencies of the Fourier spectrum.
double[]	getNaturalOmega() Gets the angular frequencies of the Fourier spectrum.
boolean	isRadians() Gets the radians flag.
double[]	repeatAnalysis(double[] y) Repeats the Fourier analysis of the real data y[] with the previously set scale and gutter.
void	useRadians(boolean radians) Sets the radians flag for the frequency values of datasets.

Methods inherited from class java.lang.Object

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

Constructor Detail

FourierSinCosAnalysis

public FourierSinCosAnalysis()

Method Detail

doAnalysis

public double[] doAnalysis(double[] x,
                           double[] y,
                           int gutter)

Fourier analyzes the given data y[] after adding gutter points at the start and end of the z[] array.

Parameters:

x - double[]

y - double[]

gutter - int

Returns:

double[] the Fourier spectrum

repeatAnalysis

public double[] repeatAnalysis(double[] y)

Repeats the Fourier analysis of the real data y[] with the previously set scale and gutter.

Parameters:

y - double[]

Returns:

double[] the Fourier sin/cos coefficients

getNaturalOmega

public double[] getNaturalOmega()

Gets the angular frequencies of the Fourier spectrum.

Returns:

double[]

getNaturalFreq

public double[] getNaturalFreq()

Gets the frequencies of the Fourier spectrum.

Returns:

double[]

useRadians

public void useRadians(boolean radians)

Sets the radians flag for the frequency values of datasets. Dataset x-values are either frequencies (cycles) or angular frequencies (radians) depending on the value of the radians flag.

Parameters:

radians - boolean

isRadians

public boolean isRadians()

Gets the radians flag. Radians is true if the dataset uses angular frequency as the x-coordinate.

Returns:

boolean

getComplexDatasets

public java.util.ArrayList getComplexDatasets()

Complexdatasets are not available.

Specified by:

getComplexDatasets in interface Data

Returns:

list of ComplexDatasets

getDatasets

public java.util.ArrayList getDatasets()

Gets the datasets that contain the result of the last Fourier analysis. The power spectrum is contained in the first dataset. Sine coefficients are contained in the second dataset. Cosine coefficients are in the third dataset. Dataset x-values are either frequencies (cycles) or angular frequencies (radians) depending on the value of the radians flag.

Specified by:

getDatasets in interface Data

Returns:

list of Datasets

getData2D

public double[][] getData2D()

Gets the frequencies, power, cos, and sin coefficients.

Specified by:

getData2D in interface Data

Returns:

double[][]

getData3D

public double[][][] getData3D()

3D data is not available.

Specified by:

getData3D in interface Data

Returns:

double[][][]