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Dave Seaman  
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 More options Sep 10 2003, 10:10 am
Newsgroups: comp.lang.fortran
From: Dave Seaman <dsea...@no.such.host>
Date: Wed, 10 Sep 2003 14:01:10 +0000 (UTC)
Local: Wed, Sep 10 2003 10:01 am
Subject: Re: Newbie Question...
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On 10 Sep 2003 04:22:55 -0700, Andrea wrote:

> Hello Fortran Gurus,
>     I'm not an expert with fortran, but I would like to ask 2
> questions:
> 1) Is there a fortran function/subroutine that returns the indices of
> a vector (matrix) X that are non-zero? (for whom that know matlab,
> like the "find" function).

In what form do you need the indices?  Will a logical array help?  There are
lots of ways to use such arrays in vector operations.

    program bittest

      implicit none

      integer, parameter :: n = 5
      real               :: a(n) = (/ 1.0, 0.0, 2.0, 0.0, 0.0 /)
      logical            :: flag(n)

      flag = a /= 0.0   ! the "/=" operator is sometimes spelled ".ne."

      print *, flag

    end program bittest

This program prints

 T F T F F

--
Dave Seaman
Judge Yohn's mistakes revealed in Mumia Abu-Jamal ruling.
<http://www.commoncouragepress.com/index.cfm?action=book&bookid=228>


 
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