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 From: anyili_at_[hidden] Date: 2007-07-11 19:00:55 Next message: Jelena Pjesivac-Grbovic: "Re: [OMPI users] MPI_Reduce problem" Previous message: Ralph Castain: "Re: [OMPI users] Recursive use of "orterun" (Ralph H Castain)" Next in thread: Jelena Pjesivac-Grbovic: "Re: [OMPI users] MPI_Reduce problem" Reply: Jelena Pjesivac-Grbovic: "Re: [OMPI users] MPI_Reduce problem" Hi,   I have a code which have a identical vector on each node, I am going to do the vector sum and return result to root. Such like this,   int* ttt = (int*)malloc(2 * sizeof(int));   ttt[0] = myworldrank + 1;   ttt[1] = myworldrank * 2;    MPI_Allreduce(ttt, ttt, 2, MPI_INT, MPI_SUM, MPI_COMM_WORLD);   FOR_WORLDNODE0 printf("%d, %d\n" , ttt[0],ttt[1]);   myworldrank is the rank of local node, if I run this code under 4 nodes, what I expect return is 10,12. But what I got is 18,24. So I'm confused here on MPI_Reduce, is that supposed to do the vector sum ?   I tried MPI_Allreduce, it gave me the correct answer 10, 12.   Is there someone met the same problems or I am wrong on calling MPI_Reduce()   Thanks. Anyi   Next message: Jelena Pjesivac-Grbovic: "Re: [OMPI users] MPI_Reduce problem" Previous message: Ralph Castain: "Re: [OMPI users] Recursive use of "orterun" (Ralph H Castain)" Next in thread: Jelena Pjesivac-Grbovic: "Re: [OMPI users] MPI_Reduce problem" Reply: Jelena Pjesivac-Grbovic: "Re: [OMPI users] MPI_Reduce problem"