for(k=0;k<fourier->data_len[dim];k++) {
fourier->ftdata[dim][k].r=0;
fourier->ftdata[dim][k].i=0;
for(i=0;i<fourier->data_len[dim];i++) {
/* f(k) = 1/N sum(n=0-N) f(n) exp(-i*k*2*PI*n/N) */
arg=-1.0*k*M_PI*i/fourier->data_len[dim];
for(k=0;k<fourier->data_len[dim];k++) {
fourier->ftdata[dim][k].r=0;
fourier->ftdata[dim][k].i=0;
for(i=0;i<fourier->data_len[dim];i++) {
/* f(k) = 1/N sum(n=0-N) f(n) exp(-i*k*2*PI*n/N) */
arg=-1.0*k*M_PI*i/fourier->data_len[dim];