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97 lines
2.8 KiB
Fortran
97 lines
2.8 KiB
Fortran
! This is part of the netCDF package.
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! Copyright 2008 University Corporation for Atmospheric Research/Unidata.
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! See COPYRIGHT file for conditions of use.
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! This is a simple example which reads a small dummy array, from a
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! netCDF data file created by the companion program
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! simple_xy_par_wr.f90. The data are read using parallel I/O.
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! This is intended to illustrate the use of the netCDF fortran 90
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! API. This example program is part of the netCDF tutorial, which can
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! be found at:
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! http://www.unidata.ucar.edu/software/netcdf/docs/netcdf-tutorial
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! Full documentation of the netCDF Fortran 90 API can be found at:
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! http://www.unidata.ucar.edu/software/netcdf/docs/netcdf-f90
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! $Id: simple_xy_par_rd.f90,v 1.2 2009/03/12 18:30:41 ed Exp $
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program simple_xy_par_rd
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use netcdf
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implicit none
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include 'mpif.h'
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! This is the name of the data file we will read.
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character (len = *), parameter :: FILE_NAME = "simple_xy_par.nc"
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! These will tell where in the data file this processor should
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! write.
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integer, parameter :: NDIMS = 2
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integer :: start(NDIMS), count(NDIMS)
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! We will read data into this array.
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integer, allocatable :: data_in(:)
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! This will be the netCDF ID for the file and data variable.
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integer :: ncid, varid
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! MPI stuff: number of processors, rank of this processor, and error
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! code.
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integer :: p, my_rank, ierr
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! Loop indexes, and error handling.
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integer :: x, y, stat
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! Initialize MPI, learn local rank and total number of processors.
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call MPI_Init(ierr)
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call MPI_Comm_rank(MPI_COMM_WORLD, my_rank, ierr)
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call MPI_Comm_size(MPI_COMM_WORLD, p, ierr)
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! Allocate space to read in data.
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allocate(data_in(p), stat = stat)
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if (stat .ne. 0) stop 3
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! Open the file. NF90_NOWRITE tells netCDF we want read-only access to
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! the file.
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call check( nf90_open(FILE_NAME, NF90_NOWRITE, ncid, comm = MPI_COMM_WORLD, &
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info = MPI_INFO_NULL) )
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! Get the varid of the data variable, based on its name.
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call check( nf90_inq_varid(ncid, "data", varid) )
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! Read the data.
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start = (/ 1, my_rank + 1/)
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count = (/ p, 1 /)
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call check( nf90_get_var(ncid, varid, data_in, &
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start = start, count = count) )
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! Check the data.
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do x = 1, p
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if (data_in(x) .ne. my_rank) then
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print *, "data_in(", x, ") = ", data_in(x)
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stop "Stopped"
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endif
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end do
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! Close the file, freeing all resources.
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call check( nf90_close(ncid) )
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! Free my local memory.
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deallocate(data_in)
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! MPI library must be shut down.
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call MPI_Finalize(ierr)
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if (my_rank .eq. 0) print *,"*** SUCCESS reading example file ", FILE_NAME, "! "
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contains
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subroutine check(status)
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integer, intent ( in) :: status
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if(status /= nf90_noerr) then
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print *, trim(nf90_strerror(status))
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stop 2
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end if
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end subroutine check
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end program simple_xy_par_rd
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