HP-MPI User's Guide (11th Edition)

Understanding HP-MPI
Autodouble functionality
Chapter 3 53
NOTE This autodouble feature is supported in the regular and multithreaded
MPI libraries, but not in the diagnostic library.
For Windows:
/integer_size:64
/4I8
-i8
/real_size:64
/4R8
/Qautodouble
-r8
If these flags are given to the mpif90.bat script at link time, then the
application will be linked enabling HP-MPI to interpret the datatype
MPI_REAL as 8 bytes (etc. as appropriate) at runtime.
However, if your application is written to explicitly handle the
autodoubled datatypes (e.g. if a variable is declared real and the code is
compiled -r8 and corresponding MPI calls are given MPI_DOUBLE for the
datatype), then the autodouble related command line arguments should
not be passed to mpif90.bat at link time (because that would cause the
datatypes to be automatically changed).