INTEGER*8 and DOUBLE PRECISION are implemented, however.
Here are some compiler options that may have some bearing on your problem:
(copied from info g77)
`-fno-automatic' Treat each program unit as if the `SAVE' statement was specified for every local variable and array referenced in it. Does not affect common blocks. (Some Fortran compilers provide this option under the name `-static'.)
`-finit-local-zero' Specify that variables and arrays that are local to a program unit (not in a common block and not passed as an argument) are to be initialized to binary zeros.
Since there is a run-time penalty for initialization of variables that are not given the `SAVE' attribute, it might be a good idea to also use `-fno-automatic' with `-finit-local-zero'.
Lot's of time the "nan" problem is caused by un-initialized variables, and the two options above are done by default in some fortran compilers.
regards, bud davis