Greg,

Be careful when you say:

The Fortrans are compatible enough that a single MPI library can deal
with all. The calling convention stuff happens to work because MPI
doesn't happen to have any calls that hit the "f2c abi" issue. The
underscore thing can be handled with multiple symbols for each entry
point.
-- greg

We've just spent several days of debugging a large scientific code eventually to find that calling a routine with LOGICAL parameters that was compiled with pathf90, from a routine compiled with pgf90 does not work.

It transpires that the machine representation for fortran logicals are different between the two compilers, as shown below

            TRUE    FALSE
pathf90       1       0
pgf90        -1       0

(Note that using pgf90 options  -Munixlogical -Mnounixlogical does not change the value stored by pgf90 logicals)


This is an example where you have to be very careful coding and using an ABI.

Regards
       Neil
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