Intel fortran-80 manual 5.2.5SAVE Statement, 5.2.6EXTERNAL Statement, SAVE lebl ,Iebl

FORTRAN-SO Functions And Subroutines

When a RETURN is executed in a FUNCTION subprogram, the value of the func- tion must be available to the referencing program unit.

Whenever RETURN is executed, the association between the dummy arguments of an external procedure and the current actual arguments is terminated (but see sec- tion 5.2.5, the SA VE statement).

Example:

C TH REE NUM BERS ARE ADDED AN D TH E FLAG 'POSTorSET TO C TO 11F THEIR TOTAL IS POSITIVE

SUBROUTINE POSTOT(A,B,C)

IF ((A + B + C) .GE. 0) THEN POSTOT = 1

ELSE POSTOT = 0

ENDIF

RETURN END

5.2.5SAVE Statement

The SAVE statement can be used to make sure that common variables within a FUNCTION or SUBROUTINE subprogram do not become undefined when a RETURN or END is executed.

The format of the SAVE statement is

SAVE lebl [,Iebl] ...

where 'cb' is a named common block. Naming the common block saves all items in that block. A specific common bloj:k cannot be listed more than once in a single SA VE statement. Entities in blank common never become undefined as the result of executing RETURN or END.

Example:

SAVE IBLOCK1/,/BLOCK21

5.2.6EXTERNAL Statement

The EXTERNAL statement confirms that a symbolic name represents an external or dummy procedure and allows that name to be used as an actual argument.

The format of the EXTERNAL statement is

EXTERNAL proe [,proe] ...

where 'proc' is the name of an external or dummy procedure.

If an intrinsic function name is specified in an EXTERNAL statement, that name can no longer be used to specify an intrinsic function in the program unit, but in- stead becomes the name of an external procedure.

A symbolic name can be specified only once in all the EXTERNAL statements in a program unit.

Example:

EXTERNAL HYP, POSTOT, SIN

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