To add intrinsic functions or change them in the FORTRAN compiler:
1. Modify /usr/src/cmd/f77/intr.c of compiler if the type is to be
   set automatically by the compiler and several alternate C
   routines exist for separate types.
2. Put function source in this directory.
3. Add function name to makefile.
            PLWard USGS, Menlo Park 10/15/79