Example of Using EXTERNAL for User-Defined Function (50401)

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This article was previously published under Q50401

SUMMARY

In a FORTRAN application, the EXTERNAL statement specifies that a user-defined name is a subroutine or function that can be used as a formal argument. In addition, an application can use the EXTERNAL statement to replace an intrinsic function with a user-defined function of the same name.

The following code example demonstrates using the EXTERNAL command to specify a user-defined function in a FORTRAN application.

Sample Code

C Compile options needed: None

      FUNCTION FN (X)
        REAL FN, X
        FN = X
      END

      SUBROUTINE S2 (F, X, Y)
        REAL F, X, Y
        X = F(Y)
      END

      REAL Y, Z, FN
      EXTERNAL FN
      Z = 10.0
      CALL S2(FN, Y, Z)
      WRITE (*, *) Y
      END

Modification Type:

Major

Last Reviewed:

12/1/2003

Keywords:

kbLangFortran KB50401