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Re: Expand [message #10620 is a reply to message #733]

Mon, 05 January 1998 00:00

davidf
Messages: 2866
Registered: September 1996

Senior Member

Kelly Dean (krdean@lamar.colostate.edu) writes:

> I am reading some AVHRR LAC data in the Level 1B format. The image
> provides 51 latitude/longitude pairs for each 2048 pixel scan line. They
> are sampled every 40 points starting at point 25 (25, 65, 105,..., 1945,
> 1985, 2025).
>
> I created a simple IDL routine to expand the 51 values to 2048 values
> using FOR loops. I am looking for suggestions to make this more
> efficient.

Uh, why? It's pretty darn fast on my middling machine. :-)

[Code snipped.]

I don't think you can get rid of the outside loop (stepping
between the known points), but you can speed up the inside
loop I guess (interpolating values between the known points)
by doing something like this:

FOR j=25, 1985, 40 DO BEGIN
array2048(j:j+39) = Findgen(40) * $
((value[j+39]-value[j])/39) + value[j]
ENDFOR

Cheers,

David

-----------------------------------------------------------
David Fanning, Ph.D.
Fanning Software Consulting
E-Mail: davidf@dfanning.com
Phone: 970-221-0438
Coyote's Guide to IDL Programming: http://www.dfanning.com/

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[Message index]

		EXPAND.PRO - - - again! By: zawodny on Thu, 29 October 1992 04:11
		Re: Expand By: Kelly Dean on Tue, 06 January 1998 00:00
		Re: Expand By: Kelly Dean on Tue, 06 January 1998 00:00
		Re: Expand By: Kevin Ivory on Tue, 06 January 1998 00:00
		Re: Expand By: davidf on Mon, 05 January 1998 00:00

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