bijnum

## Class BIJfft

• ```public class BIJfft
extends Object```
This class implements a one-dimensional real-to-complex fast fourier transform Copyright (c) 1999-2004, Michael Abramoff. All rights reserved.
• ### Field Summary

Fields
Modifier and Type Field and Description
`protected double[]` `C`
`protected double[]` `dx`
`protected int` `n`
Local variables used in BIJfht algorithms.
`protected int` `n2`
Local variables used in BIJfht algorithms.
`protected int` `nu`
Local variables used in BIJfht algorithms.
`protected int` `nu1`
Local variables used in BIJfht algorithms.
`protected double[]` `S`
`protected float[]` `x`
• ### Constructor Summary

Constructors
Constructor and Description
`BIJfft(double[] dx)`
Set up a BIJfft a matrix x of length power of 2.
`BIJfft(float[] x)`
Set up a BIJfft a matrix x of length power of 2.
• ### Method Summary

All Methods
Modifier and Type Method and Description
`protected int` `bitrev(int j)`
`float[]` `compute(float[] x)`
Compute the 1-D Fast fourier transform for x.
`float[][]` `compute2(float[] x)`
`static double[]` `extend(double[] x)`
`static double[]` `extend(float[] x)`
`double[]` `mag()`
Compute power spectrum of FFT 1-D.
`protected void` `makeSinCosTables()`
Calculate the sin and cos tables for the current vector length.
`protected void` `progress(double percent)`
Can be used to show progress in other programs.
`static void` `testsin(float[] wave)`
• ### Methods inherited from class java.lang.Object

`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`
• ### Field Detail

• #### n

`protected int n`
Local variables used in BIJfht algorithms.
• #### nu

`protected int nu`
Local variables used in BIJfht algorithms.
• #### n2

`protected int n2`
Local variables used in BIJfht algorithms.
• #### nu1

`protected int nu1`
Local variables used in BIJfht algorithms.
• #### C

`protected double[] C`
• #### S

`protected double[] S`
• #### dx

`protected double[] dx`
• #### x

`protected float[] x`
• ### Constructor Detail

• #### BIJfft

`public BIJfft(float[] x)`
Set up a BIJfft a matrix x of length power of 2.
Parameters:
`x` - the real array for which you will compute the 1-D FFT.
• #### BIJfft

`public BIJfft(double[] dx)`
Set up a BIJfft a matrix x of length power of 2.
Parameters:
`dx` - the real array for which you will compute the 1-D FFT.
• ### Method Detail

• #### compute

`public float[] compute(float[] x)`
Compute the 1-D Fast fourier transform for x. x must have the same length as BIJfft was initialized with to make sure all tables are still valid.
Parameters:
`x` - vector x (power 2 length)
Returns:
the power spectrum as a float[].
• #### mag

`public final double[] mag()`
Compute power spectrum of FFT 1-D. Similar implementation.
• #### progress

`protected void progress(double percent)`
Can be used to show progress in other programs.
• #### bitrev

`protected int bitrev(int j)`
• #### makeSinCosTables

`protected void makeSinCosTables()`
Calculate the sin and cos tables for the current vector length. Saves a lot of time in the main loop.
• #### testsin

`public static void testsin(float[] wave)`
• #### compute2

`public final float[][] compute2(float[] x)`
• #### extend

`public static double[] extend(double[] x)`
• #### extend

`public static double[] extend(float[] x)`

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