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Re: Polyhedron shootout between g95 and gfortran

From: Paul Thomas <paulthomas2 at wanadoo dot fr>
To: Dominique Dhumieres <dominiq at lps dot ens dot fr>
Cc: fortran at gcc dot gnu dot org
Date: Thu, 23 Feb 2006 00:52:15 +0100
Subject: Re: Polyhedron shootout between g95 and gfortran
References: <43FCEE30.mailH9C11EVO4@tournesol.lps.ens.fr>

Dominique,

induct.f90 use dot_product with length 3 vectors. A couple of months
ago Paul Thomas propsed a patch to inline the dot_product.
On a G5 (1.8Ghz) I get 295.2s without the patch and 68.4s with it.

I should add that your diagnosis is correct - dot_product is screwed up; not just on timing grounds but also because the range of quotients that it produces a good result for is quite limited. It is an occasion in which fast-math is just that and better in its output.

If somebody would like to come back and put the finishing touches to my patch, I would be very grateful.

Paul

Follow-Ups:
- Re: Polyhedron shootout between g95 and gfortran
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References:
- Re: Polyhedron shootout between g95 and gfortran
  - From: Dominique Dhumieres

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