Dear Jean, FFT generates symmetric spectra - basically symmetric mirror images. [The frequencies are mirrored against the central 0.]
This seems to be the case in the "real" image. While the "complex" image seems to include only one half, which is the usual way to represent the NMR spectrum. [and more generally any frequency-power spectrum in real life] I do not have though access to go_fft, and I am unsure what "complex data" in your post means. Sincerely, Leonard -------- Original-Nachricht -------- > Datum: Sun, 03 Oct 2010 08:41:51 +0200 > Von: Jean Brefort <jean.bref...@normalesup.org> > An: Gnumeric List <gnumeric-list@gnome.org> > Betreff: fft question > Hi, > > I'm a bit puzzled about the output of the go_fft function (actually the > same code as what we have in gnumeric, may be gnumeric might use the > goffice version?). I'm trying to use it to transform an NMR FID to a > spectrum. When I use only the real data, things give the expected > result, but I do not understand the output when I use the complex data > input (see attached images). Is there some FFT expert around? > > Regards, > Jean -- GMX DSL Doppel-Flat ab 19,99 €/mtl.! Jetzt auch mit gratis Notebook-Flat! http://portal.gmx.net/de/go/dsl _______________________________________________ gnumeric-list mailing list gnumeric-list@gnome.org http://mail.gnome.org/mailman/listinfo/gnumeric-list
