The TAO library currently interfaces to the PETSc library for
low-level system functionality as well as linear algebra support. The
PETSc users manual discusses additional Fortran issues in these areas,
including
- array arguments (e.g., VecGetArray()),
- calling Fortran Routines from C (and C Routines from Fortran),
- passing null pointers,
- duplicating multiple vectors, and
- matrix and vector indices.