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correct the fft scaling for real input and complex output vector

This commit is contained in:
dwarning 2017-08-16 21:35:41 +02:00
parent 060e0037f8
commit b8a9ca9df4
2 changed files with 4 additions and 4 deletions
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4
src/frontend/com_fft.c
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@ -172,7 +172,7 @@ com_fft(wordlist *wl)
fftw_execute(plan_forward);
scale = (double) length;
scale = (double) fpts - 1.0;
for (j = 0; j < fpts; j++) {
fdvec[i][j].cx_real = out[j][0]/scale;
fdvec[i][j].cx_imag = out[j][1]/scale;
@ -200,7 +200,7 @@ com_fft(wordlist *wl)
rffts(in, M, 1);
fftFree();
scale = (double) N;
scale = (double) fpts - 1.0;
/* Re(x[0]), Re(x[N/2]), Re(x[1]), Im(x[1]), Re(x[2]), Im(x[2]), ... Re(x[N/2-1]), Im(x[N/2-1]). */
fdvec[i][0].cx_real = in[0]/scale;
fdvec[i][0].cx_imag = 0.0;

4
src/maths/cmaths/cmath4.c
View File

@ -716,7 +716,7 @@ cx_fft(void *data, short int type, int length, int *newlength, short int *newtyp
fftw_execute(plan_forward);
scale = (double) length;
scale = (double) fpts - 1.0;
for (i = 0; i < fpts; i++) {
outdata[i].cx_real = out[i][0]/scale;
outdata[i].cx_imag = out[i][1]/scale;
@ -740,7 +740,7 @@ cx_fft(void *data, short int type, int length, int *newlength, short int *newtyp
rffts(datax, M, 1);
fftFree();
scale = (double) N;
scale = (double) fpts - 1.0;
/* Re(x[0]), Re(x[N/2]), Re(x[1]), Im(x[1]), Re(x[2]), Im(x[2]), ... Re(x[N/2-1]), Im(x[N/2-1]). */
outdata[0].cx_real = datax[0]/scale;
outdata[0].cx_imag = 0.0;