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Re: Need efficient routine to calculate max of two arrays [message #3410 is a reply to message #3402]

Thu, 26 January 1995 06:25

pa64
Messages: 3
Registered: January 1995

Junior Member

In article <3g3p8i$1o6@cobra.aer.com>, gallery@aer.com (William O. Gallery) writes:
|> Here is the problem:
|>
|> There are two arrays: a and b of equal length, I want to calculate
|> an array c of the same length so that:
|> c(i) = min(a(i),b(i))
|>
|> For efficiency, I want to use vectors and not a do loop.
|>
|> Any suggestions? This would seem to be a common enough problem,
|>
|>
|>
|> --
|> William O. Gallery gallery@aer.com
|> Atmospheric & Environmental Research Voice(617) 349-2284
|> 840 Memorial Drive (617) 547-6207
|> Cambridge, Massachusetts 02139 FAX (617) 661-6479

Up to four arrays, the following function seems to be quite efficient:

function pmin,im1,im2,im3,im4
if n_params() gt 3 then begin
index = where(im4 lt im3, count)
if count gt 0 then im3(index) = im4(index)
endif
if n_params() gt 2 then begin
index = where(im3 lt im2, count)
if count gt 0 then im2(index) = im3(index)
endif
if n_params() gt 1 then begin
index = where(im2 lt im1, count)
if count gt 0 then im1(index) = im2(index)
endif
return,im1
end

Regards,
Hermann Mannstein

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~
Hermann Mannstein Tel.: +49 8153 28-2503
Institut fuer Physik der Atmosphaere or -1118
DLR - Oberpfaffenhofen Fax.: +49 8153 28-1841
Postfach 1116 email.: H.Mannstein@dlr.de
D-82230 Wessling \
Germany \ O
________\/|________
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~`--------\--------'~ ~~~~~~~~~~~~~~~~~~~~
\

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[Message index]

		Re: Need efficient routine to calculate max of two arrays By: mfishler on Wed, 25 January 1995 17:07
		Re: Need efficient routine to calculate max of two arrays By: pa64 on Thu, 26 January 1995 06:25
		Re: Need efficient routine to calculate max of two arrays By: thompson on Wed, 25 January 1995 09:01
		Re: Need efficient routine to calculate max of two arrays By: kucera on Wed, 25 January 1995 09:17
		Re: Need efficient routine to calculate max of two arrays By: karsten on Tue, 24 January 1995 23:55
		Re: Need efficient routine to calculate max of two arrays By: kommers on Tue, 24 January 1995 18:45
		RE: Need efficient routine to calculate max of two arrays By: mallozzi on Tue, 24 January 1995 17:29
		Re: Need efficient routine to calculate max of two arrays By: dan on Tue, 24 January 1995 15:12

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