External Procedures

Fortran 90 allows a class of procedure that is not contained within a PROGRAM or a MODULE -- an EXTERNAL procedure.

This is the old FORTRAN 77-style of programming and is more clumsy than the Fortran 90 way.

Differences:

• they may be compiled separately,
• may need an explicit INTERFACE to be supplied to the calling program,
• can be used as arguments (in addition to intrinsics),
• should contain the IMPLICIT NONE specifier.

Return to corresponding overview page

• External Subroutine Syntax
  • External Subroutine Example
• External Function Syntax
  • Function Example
• Procedure Interfaces
  • Interface Example
• Required Interfaces
• Side Effect Functions
• Recursive Procedures
  • Recursive Function Example
  • Recursive Subroutine Example