All the interface routines in C has its FORTRAN version, given in interface.cpp. All FORTRAN interface routines start with f_ and can be called in FORTRAN directly.

Note: Most FORTRAN compilers mangles the subroutine names in a way that in the corresponding C code, the subroutine name should end with an underscore "_". This is controlled in make.inc, by adding -DAdd_ in the COMMONDEFS variable. This macro controls the behavior of FORTRAN() as defined in environment.hpp, as well as the internal routines such as BLAS() and LAPACK().