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6.1 Intrinsic Module Overview

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.