Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;
//License from project: Open Source License 

public class Main {
    private static double[] b = { 0.010312874762664, -0.061877248575986, 0.154693121439966, -0.206257495253288,
            0.154693121439966, -0.061877248575986, 0.010312874762664 };
    private static double[] a = { 1.000000000000000, 1.187600680175615, 1.305213349288551, 0.674327525297999,
            .263469348280139, 0.051753033879642, 0.005022526595088 };

    /**
     * applies a 6th-order butterworth highpass filter with cutoff at 0.6
     * @param data
     * @return highpass filtered data
     */
    public static double[] applyHighPassFilter(double[] data) {

        //http://dsp.stackexchange.com/questions/592/how-does-matlab-handle-iir-filters

        double xmem1, xmem2, ymem1, ymem2, xmem3, xmem4, ymem3, ymem4, xmem5, xmem6, ymem5, ymem6;
        xmem1 = xmem2 = ymem1 = ymem2 = xmem3 = xmem4 = ymem3 = ymem4 = xmem5 = xmem6 = ymem5 = ymem6 = 0.0;

        int p = 0;

        while (p < data.length) {

            double y = b[0] * data[p] + b[1] * xmem1 + b[2] * xmem2 + b[3] * xmem3 + b[4] * xmem4 + b[5] * xmem5
                    + b[6] * xmem6 - a[1] * ymem1 - a[2] * ymem2 - a[3] * ymem3 - a[4] * ymem4 - a[5] * ymem5
                    - a[6] * ymem6;

            if (Double.isNaN(y))
                y = 0.0;

            xmem6 = xmem5;
            xmem5 = xmem4;
            xmem4 = xmem3;
            xmem3 = xmem2;
            xmem2 = xmem1;
            xmem1 = data[p];
            ymem6 = ymem5;
            ymem5 = ymem4;
            ymem4 = ymem3;
            ymem3 = ymem2;
            ymem2 = ymem1;
            ymem1 = y;

            data[p] = y;

            p++;
        }
        return data;

    }
}