How do I retain precision for a Fortran MPI program in a portable way?

Question

I have a Fortran program where I specify the kind of the numeric data types in an attempt to retain a minimum level of precision, regardless of what compiler is

Answer 1

How about:

integer, parameter :: DOUBLE_PREC = kind(0.0d0)
integer, parameter :: SINGLE_PREC = kind(0.0e0)

integer, parameter :: MYREAL = DOUBLE_PREC


if (MYREAL .eq. DOUBLE_PREC) then
   MPIREAL = MPI_DOUBLE_PRECISION
else if (MYREAL .eq. SINGLE_PREC) then
   MPIREAL = MPI_REAL
else
   print *, "Erorr: Can't figure out MPI precision."
   STOP
end if

and use MPIREAL instead of MPI_DOUBLE_PRECISION from then on.