How to implement low pass filter using java

Question

I am trying to implement a low pass filter in Java. My requirement is very simple,I have to eliminate signals beyond a particular frequency (Single dimension). Looks like Bu

Answer 1

I adopted this from http://www.dspguide.com/ I'm quite new to java, so it's not pretty, but it works

/*
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package SoundCruncher;

import java.util.ArrayList;

/**
 *
 * @author 2sloth
 * filter routine from "The scientist and engineer's guide to DSP" Chapter 20
 * filterOrder can be any even number between 2 & 20


* cutoffFreq must be smaller than half the samplerate
 * filterType: 0=lowPass   1=highPass
 * ripplePercent is amount of ripple in Chebyshev filter (0-29) (0=butterworth)
 */
public class Filtering {
    double[] filterSignal(ArrayList signal, double sampleRate ,double cutoffFreq, double filterOrder, int filterType, double ripplePercent) {
        double[][] recursionCoefficients =   new double[22][2];
        // Generate double array for ease of coding
        double[] unfilteredSignal =   new double[signal.size()];
        for (int i=0; i