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#include <stdio.h>
#include <math.h>
#include <chplot.h>
#include <numeric.h>
#define N 512
int main() {
array double t[N], x[N], y[N], Pyy[N/2], f[N/2], u[7], v[7];
array double complex Y[N];
int i;
class CPlot plot;
/* The filter arguments u[i] and v[i] are designed according to the characteristic
of filter specified. In this example program, we use the designed filter to
filter the raw data. */
u[0]=1;u[1]=-5.66792131;u[2]=13.48109005;u[3]=-17.22250511;
u[4]=12.46418230;u[5]=-4.84534157;u[6]=0.79051978;
v[0]=0.00598202; v[1]=-0.02219918; v[2]=0.02645738; v[3]=0;
v[4]=-0.02645738;v[5]=0.02219918;v[6]=-0.00598202;
linspace(t,0,511);
t = t/N;
for (i=0; i<N; i++) {
x[i] = sin(2*M_PI*5*t[i]) + sin(2*M_PI*15*t[i]) + sin(2*M_PI*t[i]*30);
x[i]=x[i]+3*(urand(NULL)-0.5);
}
filter(v,u,x,y);
plotxy(t,x,"Time domain original signal","Time (second)","Magnitude ");
plotxy(t,y,"Time domain filtered signal","Time (second)","Magnitude ");
fft(Y,x);
for (i=0; i<N/2; i++)
Pyy[i] = abs(Y[i]);
linspace(f,0,N/2);
plotxy(f,Pyy,"Frequency domain Original signal","frequency (Hz)","Magnitude (db)");
fft(Y,y);
for (i=0; i<256; i++)
Pyy[i] = abs(Y[i]);
linspace(f,0,255);
plotxy(f,Pyy,"Frequency domain filtered signal","frequency (Hz)","Magnitude (db)");
}
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