Write a 3D array in Fortran using PnetCDF

[MBR MBR]

Dear all,

I'm trying to use PnetCDF to store the variables (which are 3D arrays) of
my algorithm. Good news is that it seems much simpler than PHDF5 (which I
already implemented); bad news is that I have a MPI error at runtime I
cannot understand.
Please find both the error I get and the piece of code I wrote below. It
seems to me that it should be quite simple, but I cannot figure out what is
the problem.

Any help would be greatly appreciated!

Best,

MBR

The error I get is the following:
[mypc:18412] *** An error occurred in MPI_Type_create_subarray
[mypc:18412] *** on communicator MPI_COMM_WORLD
[mypc:18412] *** MPI_ERR_ARG: invalid argument of some other kind
[mpyc:18412] *** MPI_ERRORS_ARE_FATAL: your MPI job will now abort

Here is a simplified version of the subroutine I wrote, which compiles
without problems:

subroutine output(data,x,y,z,nout,myrank)
  use pnetcdf
  use mpi_var ! contains useful variables (idim, ni, etc. see below)

  implicit none
  include 'mpif.h'

  ! idim,jdim,kdim are the number of elements in each dimension
  real(dp),dimension(idim,jdim,kdim) :: data
  real(dp), dimension(idim) :: x
  real(dp), dimension(jdim) :: y
  real(dp), dimension(kdim) :: z
  integer :: nout, myrank
  character(LEN=*) :: filename

  ! PnetCDF variables
  integer(kind=MPI_OFFSET_KIND) :: nxtot, nytot, nztot
  integer :: nout, ncid, xdimid, ydimid, zdimid
  integer, dimension(3) :: sdimid
  integer :: varid
  integer(kind=MPI_OFFSET_KIND), dimension(3) :: dims, start, count

  ! Dimensions; ni,nj,nk are the number of MPI threads per direction
  nxtot = nx*ni
  nytot = ny*nj
  nztot = nz*nk

  dims = (/ nx, ny, nz /)

  ! Get filename; nout is the number of the current output
  call get_filename(nout, filename)

  ! Create filename
  nout = nfmpi_create(MPI_COMM_WORLD, filename, NF_CLOBBER, MPI_INFO_NULL,
ncid)

  ! Define dimensions
  nout = nfmpi_def_dim(ncid, "x", nxtot, xdimid)
  nout = nfmpi_def_dim(ncid, "y", nytot, ydimid)
  nout = nfmpi_def_dim(ncid, "z", nztot, zdimid)
  sdimid = (/ xdimid, ydimid, zdimid /)

  ! Create variable
  nout = nfmpi_def_var(ncid, "var", NF_DOUBLE, 3, sdimid, varid)

  ! End of definitions
  nout = nfmpi_enddef(ncid)

  ! {x,y,z}pos corresponds to the position of the MPI thread in a 3D
cartesian grid
  start = (/ xpos, ypos, zpos /)*dims
  count = dims

  ! Write data
  nout = nfmpi_put_vara_double_all(ncid, varid, start, count, data)

  ! Close file
  nout = nfmpi_close(ncid)

end subroutine output
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