examples/smpi/NAS/LU/exchange_4.f

   1
   2 c---------------------------------------------------------------------
   3 c---------------------------------------------------------------------
   4
   5       subroutine exchange_4(g,h,ibeg,ifin1,jbeg,jfin1)
   6
   7 c---------------------------------------------------------------------
   8 c---------------------------------------------------------------------
   9
  10 c---------------------------------------------------------------------
  11 c   compute the right hand side based on exact solution
  12 c---------------------------------------------------------------------
  13
  14       implicit none
  15
  16       include 'mpinpb.h'
  17       include 'applu.incl'
  18
  19 c---------------------------------------------------------------------
  20 c  input parameters
  21 c---------------------------------------------------------------------
  22       double precision  g(0:isiz2+1,0:isiz3+1),
  23      >        h(0:isiz2+1,0:isiz3+1)
  24       integer ibeg, ifin1
  25       integer jbeg, jfin1
  26
  27 c---------------------------------------------------------------------
  28 c  local variables
  29 c---------------------------------------------------------------------
  30       integer i, j
  31       integer ny2
  32       double precision  dum(1024)
  33
  34       integer msgid1, msgid3
  35       integer STATUS(MPI_STATUS_SIZE)
  36       integer IERROR
  37
  38
  39
  40       ny2 = ny + 2
  41
  42 c---------------------------------------------------------------------
  43 c   communicate in the east and west directions
  44 c---------------------------------------------------------------------
  45
  46 c---------------------------------------------------------------------
  47 c   receive from east
  48 c---------------------------------------------------------------------
  49       if (jfin1.eq.ny) then
  50         call MPI_IRECV( dum,
  51      >                  2*nx,
  52      >                  dp_type,
  53      >                  MPI_ANY_SOURCE,
  54      >                  from_e,
  55      >                  MPI_COMM_WORLD,
  56      >                  msgid3,
  57      >                  IERROR )
  58
  59         call MPI_WAIT( msgid3, STATUS, IERROR )
  60
  61         do i = 1,nx
  62           g(i,ny+1) = dum(i)
  63           h(i,ny+1) = dum(i+nx)
  64         end do
  65
  66       end if
  67
  68 c---------------------------------------------------------------------
  69 c   send west
  70 c---------------------------------------------------------------------
  71       if (jbeg.eq.1) then
  72         do i = 1,nx
  73           dum(i) = g(i,1)
  74           dum(i+nx) = h(i,1)
  75         end do
  76
  77         call MPI_SEND( dum,
  78      >                 2*nx,
  79      >                 dp_type,
  80      >                 west,
  81      >                 from_e,
  82      >                 MPI_COMM_WORLD,
  83      >                 IERROR )
  84
  85       end if
  86
  87 c---------------------------------------------------------------------
  88 c   communicate in the south and north directions
  89 c---------------------------------------------------------------------
  90
  91 c---------------------------------------------------------------------
  92 c   receive from south
  93 c---------------------------------------------------------------------
  94       if (ifin1.eq.nx) then
  95         call MPI_IRECV( dum,
  96      >                  2*ny2,
  97      >                  dp_type,
  98      >                  MPI_ANY_SOURCE,
  99      >                  from_s,
 100      >                  MPI_COMM_WORLD,
 101      >                  msgid1,
 102      >                  IERROR )
 103
 104         call MPI_WAIT( msgid1, STATUS, IERROR )
 105
 106         do j = 0,ny+1
 107           g(nx+1,j) = dum(j+1)
 108           h(nx+1,j) = dum(j+ny2+1)
 109         end do
 110
 111       end if
 112
 113 c---------------------------------------------------------------------
 114 c   send north
 115 c---------------------------------------------------------------------
 116       if (ibeg.eq.1) then
 117         do j = 0,ny+1
 118           dum(j+1) = g(1,j)
 119           dum(j+ny2+1) = h(1,j)
 120         end do
 121
 122         call MPI_SEND( dum,
 123      >                 2*ny2,
 124      >                 dp_type,
 125      >                 north,
 126      >                 from_s,
 127      >                 MPI_COMM_WORLD,
 128      >                 IERROR )
 129
 130       end if
 131
 132       return
 133       end