uses MtxExpr, Math387, MtxVec, SignalUtils, MtxVecTee, MtxVecEdit, IIRFilters;

  procedure TForm42.Button1Click(Sender: TObject);
  var b,c,Response,Response1,sos: Vector;
      State: TIirState;
      n,i: integer;
  begin
      Tone(b,300,6/300,0,1);

  //   Alternative: try gaussian noise
  //    b := RandGauss(300);

      c.Size(b);
      ChebyshevIFilter(6,0.2,[0.6],ftLowpass,false,sos); //design filter
      FillChar(State,SizeOf(State),0);
      IirInitBQ(sos,State);  //initialize filtering structure
      try
          c.Copy(b); //make backup of data
          IirFilter(c,State); //apply filter to data

          DrawIt([b,c],['Original signal','Filtered signal']);
          FrequencyResponse(b,nil,Response,8,True,wtHanning);
          FrequencyResponse(c,nil,Response1,8,True,wtHanning);
          DrawIt([Response,Response1],['Orig. signal','Filtered']);
      finally
          IirFree(State);
      end;
  end;

  #include "MtxExpr.hpp"
  #include "MtxVecEdit.hpp"
  #include "MtxVecTee.hpp"
  #include "SignalUtils.hpp"
  #include "IIRFilters.hpp"
  #include <string.h>

  void __fastcall TForm1::BitBtn1Click(TObject *Sender)
  {
      sVector b,c, Response1, Response, sos;
      TIirState State;
      TToneState ToneState;
      int i,n;

      b.Size(300);
      ToneInit(6.0/300,0.0,1.0,ToneState,false);
      Tone(b,ToneState);  //generate data

    //   Alternative: try gaussian noise
    //   b.RandGauss();

      ChebyshevIFilter(6,0.2,OPENARRAY(double,(0.6)),ftLowpass,false,sos);
      memset(&State,0,sizeof(State));
      IirInit(sos,State);
      try
      {
              c.Copy(b);  //backup data
              IirFilter(c,State);  //apply filter to the data

          DrawIt(OPENARRAY(TVec*,(b,c)),OPENARRAY(AnsiString,("Original signal","Filtered Signal")));
          FrequencyResponse(b,NULL,Response,8,True,wtHanning);
          FrequencyResponse(c,NULL,Response1,8,True,wtHanning);
          DrawIt(OPENARRAY(TVec*,(Response,Response1)),OPENARRAY(AnsiString,("Spectrum: original signal","Spectrum: filtered signal")));
      }
      __finally
      {
        IirFree(State);
      }
  }