[Scilab-users] FFT - upward continuation of a 2D grid

[arctica1963]

Hi Rafael,

Problem solved with your guidance! The cellsize was in decimal degrees, so
converted to linear units 0.016666 degrees = 1850m approx.

//dxy = 0.016666666; decimal degrees - 1 arc minute
dxy = 1850;
dkx=1/(nx*dxy);
dky=1/(ny*dxy);

...

fft_clean=clean(fft2(Boug_corr));
k=fftshift(k);

Fup=fft_clean.*exp(-2*%pi*k*uc); // needed to be angular k

F_real=real(ifft(Fup));

fftshift was applied wrong, so thanks for spotting that!

All I need to do to finish this is pad the grid, run the fft, and clip it
back to the original size. A rough check of the output compared to that from
GMT is minor

Thanks again!



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