[GiNaC-list] Ginac and OpenMP

[Martin Ettl]

-------- Original-Nachricht --------
> Datum: Wed, 19 May 2010 17:37:44 +0200
> Von: "Martin Ettl" <ettl.martin at gmx.de>
> An: jros at unavarra.es, GiNaC discussion list <ginac-list at ginac.de>
> Betreff: [GiNaC-list] Ginac and OpenMP

> Hello,
> 
> i try to do some symbolic computation in parallel using openMP. This is
> offered from gcc since version 4.2 on Linux.
> 
> Here a reduced version of what i have tried:
> 
> #include <iostream>
> #include <stdexcept>
> #include <ginac/ginac.h>
> #include <omp.h>
> using namespace std;
> using namespace GiNaC;
> 
> 
> int main()
> {
> 
>     symbol omega("om"),u("u"),du("du");
>     ex F = -(pow(omega,12)*u) - (pow(u,13));
>     unsigned int ui;
>     #pragma omp parallel for private(F) shared(ui,u,omega,du)
>     for(ui = 0; ui < 10 ; ui++)
>         std::cout << F.diff(u,ui) << std::endl;
>            
> }
> 
> Compile it with : g++ -fopenmp -o test test.cpp -lginac
> 
> For every iteration of the for loop, the result is still zero.
> Has anybody else have had the same (or similiar) problem. Have i made
> misst something?
> 
> Many thanks in advance
> 
> Martin
BTW,

switching off OpenMP prints the following correct result:

-om^12*u-u^13
-13*u^12-om^12
-156*u^11
-1716*u^10
-17160*u^9
-154440*u^8
-1235520*u^7
-8648640*u^6
-51891840*u^5
-259459200*u^4

Maybe Ginac is not usable with OpenMP?

Cheers,

Martin


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