FORTRAN


Introduction
Applications
FORTRAN Utilization on MVS (Batch Mode)
Example Programs
Related Documentation

Introduction

This documentation provides instructions for running FORTRAN jobs at the University of South Carolina.  Included are instructions for running the various compilers in batch mode (on MVS).  For the user who needs more than a general introduction to FORTRAN, sources of additional documentation are listed at the end.  This documentation was produced by the Academic Research and Data Center of USC.  Questions about its content should be referred to a FORTRAN consultant at 777-6865.

Applications

The acronym FORTRAN is made up of the initial letters of the words FORmula TRANslation and, as the words imply, FORTRAN is particularly useful in scientific, engineering, and mathematical applications requiring numerical computation.  FORTRAN was one of the first high-level programming languages and, consequently, is widely available today.

The FORTRAN compilers available at the University of South Carolina:

IBM VS FORTRAN, Version 2.6.0 in batch mode

The remainder of this documentation describes the available FORTRAN processors under MVS and CMS.

FORTRAN Utilization on MVS (Batch Mode)


IBM VS FORTRAN

NOTE: The default language level for release 2.6.0 of VS FORTRAN is 77.  The symbolic parameter LANGLVL is no longer included in the cataloged procedures.  You must remove 'LANGLVL=77' or 'LANGLVL=66' from any EXEC statements that invoke the IBM VS FORTRAN.  However, LANVLVL(66) is still available if required.

The JCL for running a program using VS FORTRAN 2.6.0 follows: 


Compile Only:
          JOB statement
     // EXEC FORTVC
     //FORT.SYSIN DD *
          FORTRAN source program

Compile and Link Edit:
          JOB statement
     // EXEC FORTVCL
     //FORT.SYSIN DD *
          FORTRAN object program
     //GO.SYSIN DD *
          Data (if any)
     //

Compile and Execute:
          JOB statement
     // EXEC FORTVCG
     //FORT.SYSIN DD *
          FORTRAN source program
     //GO.SYSIN DD *
          Data (if any)
     //

Compile, Link Edit, and Execute:
          JOB statement
     // EXEC FORTVCLG
     //FORT.SYSIN DD *
          FORTRAN source program
     //GO.SYSIN DD *
          Data (if any)
     //

Execute a compiled and linked program that is saved in a private pds (partitioned data set) on MVS DASD: 

          JOB statement
     // EXEC FORTVG
     //STEPLIB DD
     //        DD DSN=userid.prog.lib,DISP=SHR
     //GO.SYSIN DD *
          FORTRAN unit 5 input here (if any)
     /*
          Other DD statements for units other than 5, 6, & 7 here.
     //
The default region for the GO step in FORTVCLG, FORTVCG, and FORTVG cataloged procedures is 1M (1024K) bytes.  To request more region for the execution (GO) step, code the symbolic parameter GOREGN on the EXEC statement that invokes FORTVCLG, FORTVCG, or FORTVG. 

  Example:    //  EXEC FORTVCLG,GOREGN=4096K
The stepnames are the same in all of the VS$FORTRAN cataloged procedures. 

       Stepname                Step Function
       --------                -------------
        FORT                  Compilation step
        LKED                  Linkage editor step
        GO                    Execution step
To link a subroutine library at the LKED step in FORTVCLG, use the following JCL (same for LKED-step in FORTCL as well): 

          JOB statement
     // EXEC FORTVCLG
     //FORT.SYSIN DD *
          FORTRAN source program
     //LKED.SYSLIB DD
     //            DD DSN=subroutine.lib.dsn,DISP=SHR
     //GO.SYSIN DD *
          Data (if any)
     //
Any main program compiled by the current VS FORTRAN compiler (release 2.6.0) that calls subroutines compiled by other FORTRAN compilers (e.g., G, G1, or H ext.) or versions of VS FORTRAN before release 1.2.0 may have execution problems due to the current MVS/ESA operating system.
For example, FORTRAN programs calling subroutines in IMSL may abend with an 0C4 and programs calling plotting subroutines may produce a 'UNIT NUMBER OUT OF RANGE' message.  The reason for such messages is that the compiler tells the linkage editor that the address mode of the program can be either 24 or 31 bit.  While this is true for the main routine, the old subroutines may execute only in 24 bit address mode. To remedy this situation, add the AMODE parm to the linkage edit step in the case of FORTVCLG.  This is accomplished by overriding the PARM parameter in the cataloged procedure as follows: 

For FORTVCLG:
     // EXEC FORTVCLG,PARM.LKED='LET,LIST,XREF,AMODE=24'

For FORTVCG:
     // EXEC FORTVCG,PARM.GO='LET,NORES,EP=MAIN,AMODE=24'
An alternate approach for FORTVCLG is to add the following DD statement and data cards to the linkage edit step: 

     //LKED.SYSIN DD *
      MODE AMODE(24)


Example Programs

The following example illustrates how a FORTRAN program might be set up using the VS FORTRAN compiler under MVS (batch mode).  The simple program in this example computes gross pay, given hours worked and rate of pay.  Input to the program is included in the job stream (following the //GO.SYSIN DD *). 


          JOB statement
     //STEP1 EXEC FORTVCLG
     //FORT.SYSIN DD *
     C
     C PAYROLL PROGRAM
     C
        WRITE(6,101)
      101 FORMAT(1H1,10X,'HOURS WORKED',10X,'PAY RATE',10X,
       *  'GROSS PAY',/)
       1 READ(5,102,END=99) HRS, RATE
      102 FORMAT(F3.1,F4.3)
        GROSS= HRS * RATE
        OVER= HRS - 40.0
        IF(OVER.GT.0.0) GROSS= GROSS + (.5*OVER*RATE)
        WRITE(6,103) HRS, RATE, GROSS
      103 FORMAT(14X,F4.1,16X,F5.3,13X,'$',F6.2)
        GO TO 1
      99 STOP
        END
     //GO.SYSIN DD *
     4003100
     3753100
     4005000
     4508000
     2503750
     //
Following is the output produced by this program: 

     HOURS WORKED   PAY RATE   GROSS PAY
      40.0       3.100     $124.00
      37.5       3.100     $116.25
      40.0       5.000     $200.00
      45.0       8.000     $380.00
      25.0       3.750     $ 93.75

Related Documentation

As mentioned above, this documentation provides only the most general information on FORTRAN.  Following are more detailed FORTRAN references.

IBM Manuals

Detailed information can be obtained from the following IBM manuals, available for use in the CS Reference Room (third floor, CS Building, 1244 Blossom Street) and for purchase from IBM.

VS FORTRAN Version 2 Language and Library Reference (SC26-4221)
VS FORTRAN Version 2 Programming Guide (SC26-4222)
VS FORTRAN Version 2 Reference Summary - Pocket Guide (SX26-3751)
VS FORTRAN Version 2 General Information (GC26-4219)


Other Documentation

In addition to these manuals, documentation on various topics related to computer use at USC are available at ARDC Documentation, and at ARS Handouts, and the CS Reference Room.  The following is documentation that is relevant to material presented in this discussion:

JCL -- documents JOB Control Language used in running batch jobs.
SUBMIT -- documents general procedures for submitting batch jobs from VM/CMS.

ARDC Documentation     ARDC Home Page     USC Home Page    

This page updated September 17, 1999 by Amy W. Yarbrough, Academic Research and Data Center.
Copyright © 1999, The Board of Trustees of the University of South Carolina.
URL http://www.sc.edu/ardc/docs/fortran.htm