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Date:         Mon, 21 Jan 2008 09:55:17 -0500
Reply-To:     "Richard A. DeVenezia" <rdevenezia@WILDBLUE.NET>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         "Richard A. DeVenezia" <rdevenezia@WILDBLUE.NET>
Organization: Internet News Service
Subject:      Re: Largest value in a symmetric matrix
Comments: To: sas-l@uga.edu

Stefan Pohl wrote: > Hi SAS-group, > > I want to know which is the largest value in the following matrix > > id var1 var2 var3 var4 > 1 0 1 2 1 > 2 1 0 5 4 > 3 2 5 0 3 > 4 1 4 3 0 > > the matrix is symmetric > > How can I do this?

You can use the MAX function and a retained variable.

------ data _null_; retain maxvalue;

set MyData end=end; maxvalue = max (maxvalue, of var1-var4);

if end then call symputx('maxvalue',maxvalue); run;

------ The issue of symmetry does not come into play. A more complex looping approach that is symmetry aware could perform 1/2 the number of comparisons to arrive at the answer. This does not mean it would always take less time -- the MAX function might be able to loop faster internally than some externally managed loop.

-- Richard A. DeVenezia http://www.devenezia.com/


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