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From: dodson@convex.COM (Dave Dodson)
Newsgroups: comp.lang.fortran
Subject: Re: MAX function, but carry sign
Message-ID: <1991Apr12.151639.18041@convex.com>
Date: 12 Apr 91 15:16:39 GMT
References: <282@venice.water.ca.gov>
Sender: usenet@convex.com (news access account)
Reply-To: dodson@convex.COM (Dave Dodson)
Organization: Convex Computer Corporation, Richardson, Tx.
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Nntp-Posting-Host: mozart.convex.com

In article <282@venice.water.ca.gov> rfinch@caldwr.water.ca.gov (Ralph Finch) writes:
>
>I wish to use the max function on absolute values, but carry the sign
>of the original values. That is:
>
>a=max(abs(a1),abs(a2)) ! but a has sign of either a1 or a2
>
>I'm doing this with an IF statement now but wonder if there isn't some
>combination of max and sign that will give the same result without an
>IF statement.

Try the following:

a=sign(max(abs(a1),abs(a2)),(1+sign(1,abs(a1)-abs(a2)))*a1+(1-sign(1,abs(a1)-abs(a2)))*a2)

It even makes the IF statement look good, doesn't it?

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Dave Dodson		                             dodson@convex.COM
Convex Computer Corporation      Richardson, Texas      (214) 497-4234