- if(fourier->dim==0) {
- fprintf(fourier->outfd,"[fourier] dimension not specified\n");
- return F_DIM_ERROR;
- }
- for(i=0;i<fourier->dim;i++) {
- if(fourier->data_len[i]==0) {
- fprintf(fourier->outfd,"[fourier] invalid data len for dim %d\n",i);
- return F_DLEN_ERROR;
+
+
+ return F_SUCCESS;
+}
+
+int fourier_dft_1d(t_fourier *fourier) {
+
+ int i,k;
+ double arg;
+
+ if(fourier->type&FWD) {
+ for(k=0;k<fourier->data_len[0];k++) {
+ fourier->ftdata[k].r=0;
+ fourier->ftdata[k].i=0;
+ for(i=0;i<fourier->data_len[0];i++) {
+ /* f(k) = 1/N sum(n=0-N) f(n) exp(-i*k*2*PI*n/N) */
+ arg=-2.0*k*M_PI*i/fourier->data_len[0];
+ fourier->ftdata[k].r+=(cos(arg)*fourier->data[i].r-sin(arg)*fourier->data[i].i);
+ fourier->ftdata[k].i+=(sin(arg)*fourier->data[i].r+cos(arg)*fourier->data[i].i);
+ }
+ fourier->ftdata[k].r/=fourier->data_len[0];
+ fourier->ftdata[k].i/=fourier->data_len[0];