FFTinC

This is a FFT implementation in C that works with any input size and uses the Chirp-Z transformation for input sizes which are not radix 2.

Sample usage:

FComplex * x = calloc(5, sizeof(FComplex));
FComplex * yfwd = calloc(5, sizeof(FComplex));
FComplex * yinv = calloc(5, sizeof(FComplex));
if(!x || !yfwd || !yinv) { fprintf(stderr, "Error: Cannot allocate memory."); exit(1); }

x[0].re = 7.65; x[0].im = 0;
x[1].re = 0.45; x[1].im = -0.1;
x[2].re = 35; x[2].im = +0.1;
x[3].re = 0.15; x[3].im = -2;
x[4].re = 2.4; x[4].im = +0.2;

printf("------------\n");
timefft(yfwd,arrin, 1536);
printf("------------\n");
timeifft(yinv,arrin, 1536);
 printf("------------\n");

printf("Computed size 5-FFT:\n");
for(int i = 0; i < 5; ++i) printfcomplex(yfwd[i]);

printf("Computed size 5-IFFT:\n");
for(int i = 0; i < 5; ++i) printfcomplex(yinv[i]);