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FFTs in IDL [message #5760]

Thu, 15 February 1996 00:00

tom
Messages: 28
Registered: April 1995

Junior Member

Newsgroups: comp.lang.idl-pvwave
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Organization: Stanford University, CA USA
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Subject: IDL FFT Efficiency and Alternatives
Summary:

Does anyone know which algorithm the FFT.PRO routine uses? The manual
implies that it is the Cooley-Tukey with "convert-to-complex" algorithm.
This should be very much slower than the algorithms tailored for real
data (especially for large 2-D images like the ones I'm trying to filter).

Numerical Recipes lists some but they are the old "N = factor of 2 or die"
variety and zero padding a 1300x1024 array to 2048x1200 just seems like
a really stupid thing to do. The Winograd algorithms would be ideal here.

A related question: if I end up having to not be lazy and type in a book
algorithm, would it be faster to implement as a CALL_EXTERNAL or a native
IDL routine? I have no experience with external calls; someone told me they
can be slow due to translation (?).

Replies by email please.

Tom Berger
Center for Space Science and Astrophysics
Stanford University

tom@quake.stanford.edu

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[Message index]

		FFTs in IDL By: tom on Thu, 15 February 1996 00:00
		Re: FFTs in IDL By: Sergei Senin on Fri, 23 February 1996 00:00
		Re: FFTs in IDL By: Sergei Senin on Tue, 27 February 1996 00:00
		Re: FFTs in IDL By: Achim Hein on Tue, 27 February 1996 00:00
		Re: FFTs in IDL By: Sergei Senin on Tue, 27 February 1996 00:00
		Re: FFTs in IDL By: Achim Hein on Tue, 27 February 1996 00:00

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