fft.c

simplest fft c program

#include <stdio.h>
#include <math.h>
#include "complex.c"
#define m 10
//#ifdef m
// static int n= pow(2,m);
//#endif
#define n 1024

FILE *fp_t,*fp_f;
static int i;
static fcomplex a={0.3,0.4};
static fcomplex b={-0.5,0.6};
static fcomplex c;
static double t[1024];
static double f[1024];

void init()
{
c=Cadd(a,b);
for (i=0;i<1024;i++)
  {
  t[i]=i*0.01;
  f[i]=exp(-fabs(t[i]));
  }
}

void exchange()
{

}

void printoutput()
{
printf("m= %d\n n= %d\n",m,n);
printf("%f\n%f\n",c.r,c.i);
if (c.i>0)
printf("c=%f+%f*i\n",c.r,c.i);
else
printf("c=%f%f*i\n",c.r,c.i);
}

writeout()
{
fp_t=fopen("t.dat","w");
fp_f=fopen("f.dat","w");
for (i=0;i<1024;i++)
{
fprintf(fp_t,"t[%d]=%f\n", i,t[i]);
fprintf(fp_f,"f[%d]=%f\n", i,f[i]);
}
fclose(fp_t);
fclose(fp_f);
}

main()
{
init();
printoutput();
writeout();
}