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Compiling OpenFOAM 12 in Single Precision

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Old   April 21, 2006, 05:24
Default Hi! I have to use the splitMe
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Francesco Del Citto
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Hi!
I have to use the splitMesh utility, which doesn't work at all on OpenFOAM 1.3.
Because of the size of the mesh I have to split (is a .msh file with lots of internal faces that are walls), I'd be glad to compile OpenFOAM 1.2 in single precision (SP) mode, as I've seen it is allowed in version 1.3.
Is there a way to do this?
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Old   April 21, 2006, 09:07
Default Hello Francesco, 1: you can
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Martin Beaudoin
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Hello Francesco,

1: you can dowload a pre-compiled single-precision version of OpenFOAM from the OpenCFD Web site.

2: If you really need to recompile OpenFOAM, you first need to change the environment variable WM_PRECISION_OPTION from the default value DP to SP.

Just look-up the definition of the variable WM_PRECISION_OPTION in the file
$HOME/OpenFOAM/OpenFOAM-1.3/.OpenFOAM-1.3/bashrc (or the cshrc file in the same directory)

Once the modification is done, don't forget to source your environment by doing the following command:

# for bash
. $HOME/OpenFOAM/OpenFOAM-1.3/.OpenFOAM-1.3/bashrc

or

#for csh
source $HOME/OpenFOAM/OpenFOAM-1.3/.OpenFOAM-1.3/cshrc

(By the way, you need to do this modification as well if you want to use the pre-compiled single-precision version of OpenFOAM...)

Then, simply recompile OpenFOAM.

I plan to do the same recompilation in a very short while, so if in the process of recompiling I discover some "gotchas", I'll post them here. For example, there might be problems with paraFoam/paraView compiled in double precision and the dynamic library libPVFoamReader.so compiled in single precision.

I plan to add a little section to the Wiki Howto describing the recompilation process in single precision for OpenFOAM 1.3.
http://openfoamwiki.net/index.php/Howto_compile_O penFOAM

Good luck!

Martin
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Old   April 21, 2006, 09:29
Default Thanks Martin, but I need to b
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Francesco Del Citto
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Thanks Martin, but I need to build OpenFOAM 1.2 in SP mode.
I have already compiled OF 1.3 in SP and Debug mode, on Fedora Core 5 x86_64, but I don't know if I can do the same with OF 1.2

Francesco
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Old   April 21, 2006, 10:24
Default Francesco: AFAIK 1.2 doesn't
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Bernhard Gschaider
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Francesco:
AFAIK 1.2 doesn't support SP outOfTheBox. You might try to go to scalar.H and change

typedef double scalar;

to

typedef float scalar;

and recompile EVERYTHING. But I've never tried that and therefor can'T tell you if it will work
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Old   April 21, 2006, 11:58
Default Bummer.. I should have read yo
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Martin Beaudoin
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Bummer.. I should have read your message less quickly...

Sorry for introducing noise in the mailing list, I will try to behave for now on...

Bernhard suggestion is probably the best solution, but I have never tried it myself as well.

Good luck!

Martin
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Old   April 21, 2006, 12:05
Default Perhaps my problems with split
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Francesco Del Citto
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Perhaps my problems with splitMesh are resolved, so I'd not need to build OF 1.2 in single precision...
I hope so!
Francesco
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