i.fft

[Christine Gemuend]

Hello Grassusers,

I have a problem with i.fft and i.ifft.
What I want to do is:
I have two raster files x and y and want to do a correlation in the
frequency domain with them. For this sake, I apply i.fft on both
and afterwards I calculate with r.mapcalc: RESULT = x * conjugate(y).
On the result I wanted to apply the i.ifft, but I got a message, that
RESULT is not made by i.fft, what is true, but the invers fft has not
been calculated too. I tried the same on the files created by the
fft. They are stored in special directories in cell_misc, but this
didn't work either.
Has somebody of you done such calculations with success or could you
tell me how to do it right ?

Thanks in advance, Christine Gemuend

e-mail:christin at wm.estec.esa.nl