#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#include<conio.h>
#include<graphics.h>
void InitGraphic(void)
{int driver=DETECT,mode=0;
initgraph(&driver,&mode,"c:\\tc");
setfillstyle(1,BLACK);
bar(0,0,639,479);
return;
}
void PlotTimeSequ(float *x,int n,float scale,int space,int y1)
{int j,j1,x0,x1;
float max=0.0;
x0=(640-n*space)/2;
setcolor(WHITE);
line(x0-20,y1,640-x0+20,y1);
line(x0,y1-90,x0,y1+90);
outtextxy(x0-30,y1-80,"x(n)");
outtextxy(x0-10,y1+10,"0");
outtextxy(640-x0+5,y1-10,"n");
outtextxy(640-x0-4,y1+6,"N");
outtextxy(320-10,y1+10,"N/2");
setfillstyle(1,4);
setcolor(6);
for(j=0;j<n;j++)
{if(x[j]>max) max=x[j];
}
for(j=0;j<n;j++)
{
j1=space*j+x0;
x1=x[j]*scale/max;
line(j1,y1,j1,y1-x1);
fillellipse(j1,y1-x1,2,2);
}
return;
}
void PlotSpectrum(float *x,int n,float scale,int space,int y1)
{
int j,j1,x0,x1;
float max=0.0;
x0=(640-n*space)/2;
setcolor(WHITE);
line(x0-20,y1,640-x0+20,y1);
line(x0,y1-150,x0,y1+10);
outtextxy(x0-30,y1-140,"X(k)");
outtextxy(x0-10,y1+10,"0");
outtextxy(640-x0+5,y1-10,"k");
outtextxy(640-x0-4,y1+6,"N");
outtextxy(320-10,y1+10,"N/2");
setfillstyle(1,4);
setcolor(6);
for(j=0;j<n;j++)
{if(x[j]>max) max=x[j];
}
for(j=0;j<n;j++)
{j1=space*j+x0;
x1=x[j]*scale/max;
line(j1,y1,j1,y1-x1);
fillellipse(j1,y1-x1,2,2);
}
return;
}
void tra(float *x,float *y);
void FFT(float *xr,float *xi,int n,int inv)
{
int i,j,a,b,k,m;
int ep,arg,mt,s0,s1;
float sign,pr,pi,ph;
float *c,*s;
c=(float*)calloc(n,sizeof(float));
if(c==NULL)exit(1);
s=(float*)calloc(n,sizeof(float));
if(s==NULL)exit(1);
j=0;
if(inv==0)
{sign=1.0;
for(i=0;i<n;i++)
{xr[i]=xr[i]/n;
xi[i]=xi[i]/n;
}
}
else sign=-1.0;
for(i=0;i<n-1;i++)
{if(i<j)
{tra(&xr[i],&xr[j]);
tra(&xi[i],&xi[j]);
}
k=n/2;
while(k<=j)
{j=j-k;
k=k/2;
}
j=j+k;
}
ep=0;
i=n;
while(i!=1)
{ep=ep+1;
i=i/2;
}
ph=2*M_PI/n;
for(i=0;i<n;++i)
{s[i]=sign*sin(ph*i);
c[i]=cos(ph*i);
}
a=2;
b=1;
for(mt=1;mt<=ep;mt++)
{s0=n/a;
s1=0;
for(k=0;k<b;k++)
{i=k;
while(i<n)
{arg=i+b;
if(k==0)
{pr=xr[arg];
pi=xi[arg];
}
else{
pr=xr[arg]*c[s1]-xi[arg]*s[s1];
pi=xr[arg]*s[s1]+xi[arg]*c[s1];
}
xr[arg]=xr[i]-pr;
xi[arg]=xi[i]-pi;
xr[i]=xr[i]+pr;
xi[i]=xi[i]+pi;
i=i+a;
}
s1=s1+s0;
}
a=2*a;
b=b*2;
}
free(c);
free(s);
}
void tra(float *x,float *y)
{ float t;
t=(*x);
(*x)=(*y);
(*y)=t;
}
void signal1(int n,float *yr,float *yi)
{int i;
for(i=0;i<n;i++)
yr[i]=yi[i]=0;
for(i=0;i<4;i++)
yr[i]=1;
}
void signal2(int n,float *yr,float *yi)
{int i;
for(i=0;i<n;i++)
yr[i]=yi[i]=0;
for(i=0;i<4;i++)
yr[i]=i+1;
for(i=4;i<8;i++)
yr[i]=8-i;
}
void signal3(int n,float *yr,float *yi)
{int i;
for(i=0;i<n;i++)
yr[i]=yi[i]=0;
for(i=0;i<4;i++)
yr[i]=4-i;
for(i=4;i<8;i++)
yr[i]=i-3;
}
void signal4(int n,float *yr,float *yi)
{int i;
for(i=0;i<n;i++)
yr[i]=yi[i]=0;
for(i=0;i<n;i++)
yr[i]=cos(M_PI*i/4);
}
void signal5(int n,float *yr,float *yi)
{int i;
for(i=0;i<n;i++)
yr[i]=yi[i]=0;
for(i=0;i<n;i++)
yr[i]=sin(M_PI*i/8);
}
void signal6(int n,float *yr,float *yi)
{int i;
for(i=0;i<n;i++)
yr[i]=yi[i]=0;
for(i=0;i<n;i++)
yr[i]=0.2*cos(M_PI*i/8)+cos(M_PI*i/4)+cos(M_PI*i*20/64);
}
void signal7(int n,float *yr,float *yi)
{int i;
for(i=0;i<n;i++)
yr[i]=yi[i]=0;
for(i=0;i<n;i++)
yr[i]=cos(M_PI/4*i)+sin(M_PI/8*i);
}
void signal8(int n,float *yr,float *yi)
{int i;
for(i=0;i<n;i++)
yr[i]=cos(M_PI/4*i);
for(i=0;i<n;i++)
yi[i]=sin(M_PI/8*i);
}
void main(void)
{ float y[64],yr[64],yi[64];
int i,k=64;
int m,n;
InitGraphic();
printf("ENTER SIGNAL(1-8):");
scanf("%d",&m);
if(m!=6)
{printf("ENTER N:(8or16)");
scanf("%d",&n);
}
else
{printf("ENTER N:(16or32or64)");
scanf("%d",&n);
}
switch(m)
{case 1:signal1(n,yr,yi);break;
case 2:signal2(n,yr,yi);break;
case 3:signal3(n,yr,yi);break;
case 4:signal4(n,yr,yi);break;
case 5:signal5(n,yr,yi);break;
case 6:signal6(n,yr,yi);break;
case 7:signal7(n,yr,yi);break;
case 8:signal8(n,yr,yi);break; }
PlotTimeSequ(yr,n,60,10,130);
FFT(yr,yi,n,0);
for(k=0;k<=n;k++) y[k]=sqrt(yr[k]*yr[k]+yi[k]*yi[k]);
PlotSpectrum(y,n,100,10,400);
setcolor(6);
outtextxy(200,440,"Press any key---");
getch();
closegraph();
return;
}
