C bindings are compatible with Fortran, you mainly have to think about two issues:
* depending on the compiler / setting, the Fortran function names have one or two underlines as well as their module name prepended.
* index order for multidimensional arrays are reversed in Fortran.
Other than that the datatypes basically just work. So as long as you have C bindings this is not what I'm worried about, it's rather the overhead of the Erlang VM when compared to MPI (although for usual HPC loads this probably wouldn't even be an issue as long as it's not an order of magnitude slower, since most of them are not network bound if done right).
* depending on the compiler / setting, the Fortran function names have one or two underlines as well as their module name prepended.
* index order for multidimensional arrays are reversed in Fortran.
Other than that the datatypes basically just work. So as long as you have C bindings this is not what I'm worried about, it's rather the overhead of the Erlang VM when compared to MPI (although for usual HPC loads this probably wouldn't even be an issue as long as it's not an order of magnitude slower, since most of them are not network bound if done right).