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gyacomo/src/ppinit.F90
1a73dc547b15gather_output

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ppinit.F90
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SUBROUTINE ppinit
! Parallel environment
USE basic
use prec_const
IMPLICIT NONE
INTEGER :: version_prov=-1
! Variables for cartesian domain decomposition
INTEGER, PARAMETER :: ndims=3 ! p, kx and z
INTEGER, DIMENSION(ndims) :: dims=0, coords=0, coords_L=0, coords_R=0
LOGICAL :: periods(ndims) = .FALSE., reorder=.FALSE.
CHARACTER(len=32) :: str
INTEGER :: nargs, i, l
CALL MPI_INIT(ierr)
CALL MPI_COMM_RANK (MPI_COMM_WORLD, my_id, ierr)
CALL MPI_COMM_SIZE (MPI_COMM_WORLD, num_procs, ierr)
nargs = COMMAND_ARGUMENT_COUNT()
!
IF( nargs .GT. 1 ) THEN
DO i=1,ndims
CALL GET_COMMAND_ARGUMENT(i, str, l, ierr)
READ(str(1:l),'(i3)') dims(i)
END DO
IF( PRODUCT(dims) .NE. num_procs ) THEN
IF(my_id .EQ. 0) WRITE(*, '(a,i4,a,i4)') 'Product of dims: ', PRODUCT(dims), " is not consistent WITH NPROCS=",num_procs
CALL MPI_ABORT(MPI_COMM_WORLD, -2, ierr)
END IF
ELSE
! CALL MPI_DIMS_CREATE(num_procs, ndims, dims, ierr)
dims(1) = 1
dims(2) = num_procs
dims(3) = 1
END IF
num_procs_p = dims(1) ! Number of processes along p
num_procs_kx = dims(2) ! Number of processes along kx
num_procs_z = dims(3) ! Number of processes along z
!
!periodicity in p
periods(1)=.FALSE.
!periodicity in kx
periods(2)=.FALSE.
!periodicity in z
periods(3)=.TRUE.
CALL MPI_CART_CREATE(MPI_COMM_WORLD, ndims, dims, periods, reorder, comm0, ierr)
CALL MPI_COMM_RANK(comm0, rank_0, ierr)
CALL MPI_CART_COORDS(comm0,rank_0,ndims,coords,ierr)
!
! Partitions 3-dim cartesian topology of comm0 into 1-dim cartesian subgrids
!
CALL MPI_CART_SUB (comm0, (/.TRUE.,.FALSE.,.FALSE./), comm_p, ierr)
CALL MPI_CART_SUB (comm0, (/.FALSE.,.TRUE.,.FALSE./), comm_kx, ierr)
CALL MPI_CART_SUB (comm0, (/.FALSE.,.FALSE.,.TRUE./), comm_z, ierr)
! Find id inside the 1d-sub communicators
CALL MPI_COMM_RANK(comm_p, rank_p, ierr)
CALL MPI_COMM_RANK(comm_kx, rank_kx, ierr)
CALL MPI_COMM_RANK(comm_z, rank_z, ierr)
! Find neighbours
CALL MPI_CART_SHIFT(comm0, 0, 1, nbr_L, nbr_R, ierr) !left right neighbours
CALL MPI_CART_SHIFT(comm0, 1, 1, nbr_B, nbr_T, ierr) !bottom top neighbours
CALL MPI_CART_SHIFT(comm0, 2, 1, nbr_D, nbr_U, ierr) !down up neighbours
END SUBROUTINE ppinit
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