C# Example

Design an analog lowpass filter with transition band between 2 and 6 rad/sec and with at least 40dB attenuation at the end of the transition band and. The passband should not have more then 0.2dB ripple.

using Dew.Math;
using Dew.Math.Editors;
using Dew.Math.Units;
using Dew.Signal;
using Dew.Signal.Units;
using Dew.Math.Tee;
using Dew.Signal.Tee;

private void button1_Click(object sender, EventArgs e)
{
    Vector z = new Vector(0);
    Vector p = new Vector(0);
    Vector num = new Vector(0);
    Vector den = new Vector(0);
    Vector Response = new Vector(0);
    Vector FreqFr = new Vector(0);
    double k;
    double[] Wc = new double[1];
    int Order; //design a fifth order filter.

    Order = IIRFilters.ButterOrder(new double[2] { 2, 6 }, 0.2,40,TFilterType.ftLowPass,ref Wc,true);  //design analog protype
    IIRFilters.ButterAnalog(Order,z, p, out k);  //design analog protype
    LinearSystems.LowpassToLowpass(z, p, ref k, Wc[0]);
    LinearSystems.ZeroPoleToTransferFun(num, den, z, p, k);
    FreqFr.Length = 1000;
    SignalUtils.LogRamp(FreqFr, -1, 1);

    SignalUtils.FrequencyResponseS(num, den, FreqFr, Response, 0);
    TeeChart.DrawIt(Response, "Frequency response", false);
}