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I am trying to run this simple MPI Fortran 90 code on 4 processors. The problem is that I am not able to merge or synchronize the values of the elements of the array calculated by each processor. Here is the code:

PROGRAM TRY
USE MPI


integer status(mpi_status_size)
INTEGER                            I, J, K, II, IERR, MY_ID, NUM_PROCS, PSP
INTEGER     , PARAMETER                 :: GRIDX =8 
REAL        , DIMENSION(gridx)          :: PSI
psi=0
PRINT*, 'YASER'

 call mpi_init(ierr)
 call mpi_comm_rank(MPI_COMM_WORLD,my_id,ierr)
 call mpi_comm_size(MPI_COMM_WORLD,num_procs,ierr)

 DO I=1+MY_ID*GRIDX/NUM_PROCS, (MY_ID+1)*GRIDX/NUM_PROCS
    PSI(I)=1.0
 END DO

 **IF (MY_ID .NE. 0) THEN
    CALL mpi_send( PSI(1+MY_ID*GRIDX/NUM_PROCS:(MY_ID+1)*GRIDX/NUM_PROCS),GRIDX/NUM_PROCS,mpi_real, 0,10,mpi_comm_world,ierr)
 END IF
 IF (MY_ID .EQ. 0) THEN
    DO II=1,NUM_PROCS-1
        CALL mpi_recv(PSI(1+MY_ID*GRIDX/NUM_PROCS:(MY_ID+1)*GRIDX/NUM_PROCS),GRIDX/NUM_PROCS,mpi_real, &
        II,10,mpi_comm_world,status,ierr)
    END DO
 END IF**



 IF (MY_ID .EQ. 0) THEN
    OPEN(PSP,FILE='TRYpsi.txt')
    DO I=1, GRIDX
        WRITE (PSP,*)  PSI(I)
    END DO
    CLOSE(PSP)
 END IF

 CALL MPI_FINALIZE(IERR)
 END PROGRAM TRY

However, although each processor does its job correctly and make 'psi' equal to one, the problem is with their communication because when I open the TRYpsi.txt, I see that while the elements of the array calculated by the 0th processor are all equal to one, the other elements are all equal to zero! This means that either the 0th processor has not received the information from the other processors or the other processors have not sent the information to the other processors.

Could you please help me with mpi_send and mpi_recv?

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1 回答 1

4

看看你对 MPI_Recv 的调用。您在循环的每次迭代中都接收到相同的位置。您（可能）想要的是根据 II 的值更改第一个参数的值。

于 2012-06-18T23:25:51.843 回答