A number of intrinsic modules are provided that are available for use in programs. An intrinsic module is one that is pre-compiled or built in to the compiler system; several of these are part of Fortran 2003, others are specific to NAG.
The standard intrinsic modules from Fortran 2003 that are available are:
| ieee_arithmetic | Special facilities for IEEE floating-point arithmetic |
| ieee_exceptions | IEEE arithmetic exception handling |
| ieee_features | IEEE feature control |
| iso_c_binding | Facilities for interface to C functions |
| iso_fortran_env | Fortran-specific environmental facilities |
The non-standard intrinsic modules supplied by NAG are:
| f90_gc | Garbage collector control |
| f90_iostat | Input/output error codes (source form provided) |
| f90_kind | Kind number parameters (source form provided) |
| f90_preconn_io | File preconnection control |
| f90_stat | STAT= error codes (source form provided) |
| f90_unix_dir | Unix system functions — directories and files |
| f90_unix_dirent | Unix system functions — directory reading |
| f90_unix_env | Unix system functions — environment |
| f90_unix_errno | Unix system functions — error codes |
| f90_unix_io | Unix system functions — input/output (incomplete) |
| f90_unix_proc | Unix system functions — processes |
Note that although the above f90_unix_* modules contain Unix-specific
functions, in many cases these are also usable on Windows and Mac OS X; a
function that is not available can still be called but will return the
ENOSYS error code.