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correct fft dc scaling bug #620

This commit is contained in:
dwarning 2023-02-15 15:24:55 +01:00
parent 69ccefe092
commit 6726489f4a
2 changed files with 14 additions and 6 deletions
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6
src/frontend/com_fft.c
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@ -179,7 +179,9 @@ com_fft(wordlist *wl)
fftw_execute(plan_forward);
scale = (double) fpts - 1.0;
for (j = 0; j < fpts; j++) {
fdvec[i][0].cx_real = out[0][0]/scale/2.0;
fdvec[i][0].cx_imag = 0.0;
for (j = 1; j < fpts; j++) {
fdvec[i][j].cx_real = out[j][0]/scale;
fdvec[i][j].cx_imag = out[j][1]/scale;
}
@ -212,7 +214,7 @@ com_fft(wordlist *wl)
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_real = in[0]/scale/2.0;
fdvec[i][0].cx_imag = 0.0;
for (j = 1; j < fpts-1; j++) {
fdvec[i][j].cx_real = in[2*j]/scale;

14
src/maths/cmaths/cmath4.c
View File

@ -713,7 +713,9 @@ cx_fft(void *data, short int type, int length, int *newlength, short int *newtyp
outdata = alloc_c(fpts);
scale = (double) fpts;
for (i = 0; i < fpts; i++) {
outdata[0].cx_real = out[0][0]/scale/2.0;
outdata[0].cx_imag = out[0][1]/scale/2.0;
for (i = 1; i < fpts; i++) {
outdata[i].cx_real = out[i][0]/scale;
outdata[i].cx_imag = out[i][1]/scale;
}
@ -744,7 +746,9 @@ cx_fft(void *data, short int type, int length, int *newlength, short int *newtyp
outdata = alloc_c(N);
scale = (double) N;
for (i = 0; i < N; i++) {
outdata[0].cx_real = datax[0]/scale/2.0;
outdata[0].cx_imag = datax[1]/scale/2.0;
for (i = 1; i < N; i++) {
outdata[i].cx_real = datax[2*i]/scale;
outdata[i].cx_imag = datax[2*i+1]/scale;
}
@ -773,7 +777,9 @@ cx_fft(void *data, short int type, int length, int *newlength, short int *newtyp
fftw_execute(plan_forward);
scale = (double) fpts - 1.0;
for (i = 0; i < fpts; i++) {
outdata[0].cx_real = out[0][0]/scale/2.0;
outdata[0].cx_imag = 0.0;
for (i = 1; i < fpts; i++) {
outdata[i].cx_real = out[i][0]/scale;
outdata[i].cx_imag = out[i][1]/scale;
}
@ -798,7 +804,7 @@ cx_fft(void *data, short int type, int length, int *newlength, short int *newtyp
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_real = datax[0]/scale/2.0;
outdata[0].cx_imag = 0.0;
for (i = 1; i < fpts-1; i++) {
outdata[i].cx_real = datax[2*i]/scale;