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Re: efficient use of call_external [message #6286 is a reply to message #6282]

Wed, 22 May 1996 00:00

peter
Messages: 80
Registered: February 1994

Member

Nelson Tarr (nelson@star.net) wrote:
: I am interested in any information on the speed improvement that can
: be expected in translating parts of an IDL procedure to C. I plan on
: using "call_external" to invoke the functions within my C module.

: I am also interested in suggestions about when it is most beneficial
: to use C instead of IDL.

One rule of thumb is "Use call_external to replace the inner loop of
nested loops". That is, when you cannot avoid writing loops in IDL, you
will see tremendous improvement by replacing the inner loop(s), but much
less payback for replacing the outer loops. If you can vectorize the
inner loop (i.e. rewrite it to use IDL array operations) you will see
almost as much improvement.

If you are able to use IDL primitives and built-ins (e.g. array
addition, FFT, transposes), don't expect any gain from call_external.

Peter

--------------------------------
Peter Webb, HP Labs Medical Dept
E-Mail: peter_webb@hpl.hp.com
Phone: (415) 813-3756

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[Message index]

		Re: efficient use of call_external By: David Foster on Wed, 22 May 1996 00:00
		Re: efficient use of call_external By: peter on Wed, 22 May 1996 00:00
		Re: efficient use of call_external By: rivers on Wed, 22 May 1996 00:00

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