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Optimisation and float problem
- To: gcc-help at gcc dot gnu dot org
- Subject: Optimisation and float problem
- From: "lelievre tony" <tonylelievre at francemail dot com>
- Date: Mon, 12 Mar 2001 10:11:26 +0100
I work with a finite element code in C++. This program works well on SGI (Octane R12000, Origin200 4 * R10000).
I have tried to compile it on a PC under Windows NT. The PC is a PC Compaq AP550 833 Mhz avec 1 Go de RAM. I use Cygwin and gcc-2.95. I also use gcc-2.95 on SGI.
The problem is the following :
- when I compile with the same option as on SGI (-O2), one of the calculation (inversion of a matrix by an iterative procedure : GMRES) leads to NaN result, whereas it works well on SGI.
- when I compile with no optimisation, it also works on PC, but the time of computation is doubled...
I would like to know which of the optimisation of -O2 I should turn off to make it work well. I have already tried -O2 -ffloart-store, with no success.
Or perhaps the problem may have an other solution...
Any clue ?
Thanks a lot,
Tony LELIEVRE.
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