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tang76

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[求助] 初学MPI，以下Fortran程序请教

以下程序编译后运行：
mpiexec -n 4 test.exe

出现如下结果：
myid=          2
results(          3 )=       10
myid=          1
results(          2 )=       10
myid=          3
results(          4 )=       10
myid=          0
results(          1 )=       10
results(          1 )=       10
results(          2 )=  -842150451
results(          3 )=  -842150451
results(          4 )=  -842150451

期望所有输出结果均为10，请问哪里错了？

谢谢！

附：Fortran程序：

program test
implicit none
include 'mpif.h'

      integer::i
integer rank, size, myid, ierror,commandsize
      integer,allocatable::results(

commandsize=4
allocate(results(commandsize))
call MPI_INIT(ierror)
call MPI_COMM_SIZE(MPI_COMM_WORLD, size, ierror)
call MPI_COMM_RANK(MPI_COMM_WORLD, myid, ierror)

write(*,*)'myid=',myid
results(myid+1)=10
write(*,*)'results(',myid+1,')=',results(myid+1)
call MPI_ALLGATHER(results,commandsize,MPI_INTEGER,results,commandsize,MPI_INTEGER,MPI_COMM_WORLD,ierror)
if(myid==0)then
   do i=1,commandsize
      write(*,*)'results(',i,')=',results(i)
   enddo
endif
call MPI_FINALIZE(ierror)
deallocate(results)
end

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1楼 2011-10-24 12:46:46

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baghnac

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tang76(金币+1): 2011-10-26 00:08:22

引用回帖:

1楼: Originally posted by tang76 at 2011-10-24 12:46:46:
以下程序编译后运行：
mpiexec -n 4 test.exe

出现如下结果：
myid=          2
results(          3 )=       10
myid=          1
results(          2 )=       10
myid=          3 ...

⑴发送与接收缓冲区如果一样，会冲突
⑵接收缓冲区应大于各发送缓冲区的总大小
虽然书上没有找到这么说，但是我试出来的是这个结果
结果如下
myid=0
results(          1 )=       10
results(          2 )=          0
results(          3 )=          0
results(          4 )=          0
recvs(          1 )=       10
recvs(          2 )=          0
recvs(          3 )=          0
recvs(          4 )=          0
recvs(          5 )=          0
recvs(          6 )=       10
recvs(          7 )=          0
recvs(          8 )=          0
recvs(          9 )=          0
recvs(       10 )=          0
recvs(       11 )=       10
recvs(       12 )=          0
recvs(       13 )=          0
recvs(       14 )=          0
recvs(       15 )=          0
recvs(       16 )=       10
myid=1
results(          1 )=          0
results(          2 )=       10
results(          3 )=          0
results(          4 )=          0
myid=2
results(          1 )=          0
results(          2 )=          0
results(          3 )=       10
results(          4 )=          0
myid=3
results(          1 )=          0
results(          2 )=          0
results(          3 )=          0
results(          4 )=       10

附程序：
program test
implicit none
include 'mpif.h'

      integer::i
integer rank, size, myid, ierror,commandsize,sendcnt,recvcnt,sendssize
      integer,allocatable::results(

integer,allocatable::recvs(

commandsize=4
sendssize=16
allocate(results(commandsize))
allocate(recvs(sendssize))
call MPI_INIT(ierror)
call MPI_COMM_SIZE(MPI_COMM_WORLD, size, ierror)
call MPI_COMM_RANK(MPI_COMM_WORLD, myid, ierror)

! write(*,*)'myid=',myid
results(myid+1)=10
! write(*,*)'results(',myid+1,')=',results(myid+1)
call MPI_ALLGATHER(results,commandsize,MPI_INTEGER,recvs,commandsize,MPI_INTEGER,MPI_COMM_WORLD,ierror)
if(myid==0)then
   do i=1,commandsize
      write(*,*)'results(',i,')=',results(i)
   enddo
   do i=1,sendssize
      write(*,*)'recvs(',i,')=',recvs(i)
   enddo
endif
call MPI_FINALIZE(ierror)
deallocate(results)
end

运行结果