From:	kagel AT quasar DOT bloomberg DOT com
Date:	Tue, 18 Feb 1997 16:37:39 -0500
Message-Id:	<9702182137.AA02157@quasar.bloomberg.com >
To:	jbennett AT ti DOT com
Cc:	djgpp AT delorie DOT com
In-Reply-To:	<5du4c0$kor$1@superb.csc.ti.com> (jesse@lenny.dseg.ti.com)
Subject:	Re: Netlib code [was Re: flops...]
Reply-To:	kagel AT dg1 DOT bloomberg DOT com

   Errors-To: postmaster AT ns1
   From: jesse AT lenny DOT dseg DOT ti DOT com (Jesse Bennett)
   Newsgroups: comp.os.msdos.djgpp
   Date: 13 Feb 1997 04:12:48 GMT
   Organization: Texas Instruments
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       <5dh4gi$ek9$1 AT superb DOT csc DOT ti DOT com>
       <1997Feb12 DOT 130129 DOT 27922 AT indyvax DOT iupui DOT edu>
   Reply-To: jbennett AT ti DOT com (Jesse Bennett)
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   In article <1997Feb12 DOT 130129 DOT 27922 AT indyvax DOT iupui DOT edu>,
	   mwood AT indyvax DOT iupui DOT edu (Mark H. Wood) writes:
   > I have to ask:  why not simply code the relevant parts of your program in
   > Fortran?

   Because in my application all of the code is relevant.  The truth of
   the matter is that I have a huge investment in C code that I don't
   want to rewrite.  But, I am considering doing just that due to the
   lack of portable, high quality and high performance C libraries for
   linear algebra.  I am currently calling Fortran compiled LAPACK/BLAS
   library functions from my C code and the performance is lackluster, to
   say the least.  The problem is not with the performance of the Fortran
   code but with the memory bandwidth overhead associated with converting
   the C row-major matrices to the Fortran column-major order prior to

What conversion?  The FORTRAN is not converting you arrays.  FORTRAN and C
share a common calling convention (ignoring the facts that FORTRAN passes
string lengths and always passes pointers).  They just disagree on which
dimension to increment first.  You are not inverting the arrays are you?  Just
declare the C arrays with the indices reversed and everything will be fine.
This way FORTRAN can see it's columns where C sees rows and both can work
efficiently without copying.  Think about it!  We combine FORTRAN and C here at
Bloomberg all the time (70% of our code is still in FORTRAN) with C calling
FORTRAN and FORTRAN calling C and none of the problems that you report.

[SNIP]

-- 
Art S. Kagel, kagel AT quasar DOT bloomberg DOT com

A proverb is no proverb to you 'till life has illustrated it.  -- John Keats

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