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Re: efficient use of call_external [message #6289 is a reply to message #6282]

Wed, 22 May 1996 00:00

rivers
Messages: 228
Registered: March 1991

Senior Member

In article <4ntrfg$697@acs1.star.net>, nelson@star.net (Nelson Tarr) writes:
> 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.

The answer depends entirely upon what your IDL code does. If you were to try
to rewrite the IDL FFT routine in C, and use CALL_EXTERNAL to call it, you would
probably have to work hard to make it any faster than using IDL. On the other
hand, if you have to do some special processing on large arrays which cannot be
coded in IDL to use array primitives and/or built-in IDL functions which
handle arrays, then you can get 10-100 times speed improvement using
CALL_EXTERNAL.

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

See above, and also Chapter 12 (Efficient Programming) in the IDL User's Guide.

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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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