HOW TO CREATE SEPARATE FILES FOR SUBPROGRAMS IN FORTRAN 77:

Instructions:

1) Open up a new source file and type your subroutine. Save source file as a .F file, but do not compile it (it will not compile as there is no reference to a MAIN program).

2) Open up a new source file and type up your main program. At the top of the program type the statement INCLUDE followed by your Subprogram's filename in double quotes 
(ex. INCLUDE "SUB1.F"). The INCLUDE statement works necesarily the same as the #INCLUDE statement for C.

3) Run your main program.

  
FILE #1 (Main Program)

       INCLUDE "SUB1.F"
       CALL SUB1(5)
       STOP
       END




FILE #2 (Subprogram)

       SUBROUTINE SUB1(I)
       WRITE (6,7) 'Your number was: ', I
   7   FORMAT (1X, A17, I5)
       RETURN
       END




OUTPUT: Your number was: 5



Hope this helps,

Mike Garrett