6. Make with Fortran 90

Many people have had difficulty getting the Unix make utility to work with Fortran 90/95 compilers (owing to the existence of auxilliary files in addition to object files from the compilation of Fortran 90 modules).

6.1. External Resources

The following articles offer some help with this:

• The NAg FAQ
• Avoiding unnecessary recompilation of F90 modules, from the Department of Theoretical Chemistry at the University of Western Australia.

Alternatively, one can use the following utility:

• mkmf is a Perl script that will construct a Makefile from a study of the source code. It understands dependencies in Fortran 90 (modules and use) and the Fortran include statement.

6.2. Makefile Example

At the end of this document there is a full listing of a real-world example of a Makefile which builds a numerical/computational ocean model. Here the dependencies of particular modules on others is explicitly given so that when the source of one module is changed only necessary (i.e., dependent) modules are re-compiled.