I have a table "tab[]" with 10 elements "0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |" I am sending with the Scatterv function; 4 elements to the process 0 "|0 | 1 | 2 | 3 | 4| "and 6 elements to process 1 "| 5 | 6 | 7 | 8 | 9 | ", after I did the summation of the value" add " to each element of the received table which gives me a new table "afteradd[] "for each process, I want this time collecting the both tables "afteradd[]" and send them to the process 0, after a little research I found that there's a GATHERV function which do that but I do not know how ? program: #include <malloc.h> #include <stdlib.h> #include <stdio.h> #include <time.h> #include "math.h" #include "mpi.h" int main(int argc, char** argv) { int taskid, ntasks; int ierr, i, itask; int sendcounts[2048], displs[2048], recvcount; double **sendbuff, *recvbuff,*afteradd, buffsum, buffsums[2048]; double inittime, totaltime; const int nbr_etat = 10; double tab[nbr_etat]; for (int i = 0; i < nbr_etat; i++) tab[i] = i; int nbr_elm[2] = { 4, 6 }; int dpl[2] = { 0, 4 }; MPI_Init(&argc, &argv); MPI_Comm_rank(MPI_COMM_WORLD, &taskid); MPI_Comm_size(MPI_COMM_WORLD, &ntasks); recvbuff = (double *)malloc(sizeof(double)*nbr_etat); if (taskid == 0) { sendbuff = (double **)malloc(sizeof(double *)*ntasks);// run for 2 proc sendbuff[0] = (double *)malloc(sizeof(double)*ntasks*nbr_etat); for (i = 1; i < ntasks; i++) { sendbuff[i] = sendbuff[i - 1] + nbr_etat; } } else { sendbuff = (double **)malloc(sizeof(double *)* 1); sendbuff[0] = (double *)malloc(sizeof(double)* 1); } if (taskid == 0){ srand((unsigned)time(NULL) + taskid); for (itask = 0; itask<ntasks; itask++) { int k; displs[itask] = itask*nbr_etat; int s = dpl[itask]; sendcounts[itask] = nbr_elm[itask]; for (i = 0; i<sendcounts[itask]; i++) { k = i + s; sendbuff[itask][i] = tab[k]; printf("+ %0.0f ", sendbuff[itask][i]); } printf("\n"); } } recvcount = nbr_elm[taskid]; inittime = MPI_Wtime(); ierr = MPI_Scatterv(sendbuff[0], sendcounts, displs, MPI_DOUBLE, recvbuff, recvcount, MPI_DOUBLE, 0, MPI_COMM_WORLD); totaltime = MPI_Wtime() - inittime; buffsum = 0.0; int add = 3; afteradd = (double *)malloc(sizeof(double)*nbr_etat); for (i = 0; i<recvcount; i++) { afteradd [i]= add + recvbuff[i]; } for (i = 0; i<recvcount; i++) { printf("* %0.0f ", afteradd[i]); } printf("\n"); if (taskid == 0) { free(sendbuff[0]); free(sendbuff); } else { free(sendbuff[0]); free(sendbuff); free(recvbuff); } MPI_Finalize(); } _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss