[ncl-talk] ezfftf (NCL vs. Matlab)

[Thomas Tobian]

Dear NCL developers,

I recently worked a lot with Fourier analysis. Once, I compared the results
of forward fft function in ncl and matlab. Please find attached, an example
of FFT product for the meridional wind (V).  So in general, the amplitudes
and imaginary coefs produced by NCL and MATLAB are the same but the real
part is of opposite sign. Any idea why? What is the process to use for the
complex parts in NCL to convert back to longitude projection ? is there any
big differences if the data has longitude -180 to 180 VS. 0-360?

Cheers,
Thomas
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.ucar.edu/pipermail/ncl-talk/attachments/20150511/6f996d37/attachment.html 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: amp_V.png
Type: image/png
Size: 6098 bytes
Desc: not available
Url : http://mailman.ucar.edu/pipermail/ncl-talk/attachments/20150511/6f996d37/attachment.png 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: imag_V.png
Type: image/png
Size: 5913 bytes
Desc: not available
Url : http://mailman.ucar.edu/pipermail/ncl-talk/attachments/20150511/6f996d37/attachment-0001.png 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: real_V.png
Type: image/png
Size: 8013 bytes
Desc: not available
Url : http://mailman.ucar.edu/pipermail/ncl-talk/attachments/20150511/6f996d37/attachment-0002.png