This manual describes the Fortran 77 language specifications as implemented on the Silicon Graphics IRIS-4D series workstation. This implementation of Fortran 77 contains full American National Standard Institute (ANSI) Programming Language Fortran (X3.9-1978). It has extensions that provide full VMS Fortran compatibility to the extent possible without the VMS operating system or VAX data representation. It also contains extensions that provide partial compatibility with programs written in SVS Fortran and Fortran 66.

This manual refers to Fortran 77 as Fortran, except where specific distinctions between Fortran 77 and Fortran 66 are discussed.

The compiler can convert source programs written in VMS Fortran into machine programs executable under IRIX™.

Intended Audience

This manual is intended as a reference manual, rather than a tutorial, and assumes familiarity with an algebraic language or prior exposure to Fortran.

Corequisite Publications

This manual describes the Fortran language specifications. Refer to the Fortran 77 Programmer's Guide for information on

  • How to compile and link edit a Fortran program

  • Alignments, sizes, and variable ranges for the various data types

  • The coding interface between Fortran programs and programs written in C and Pascal

  • File formats, run-time error handling, and other information related to the IRIX operating system

  • Operating system functions and subroutines callable by Fortran programs

Refer to the IRIS-4D Series Compiler Guide for information on:

  • An overview of the compiler system

  • Information on improving the program performance, showing how to use the profiling and optimization facilities of the compiler system

  • The dump utilities, archiver, and other tools for maintaining Fortran programs

Refer to the dbx User's Reference Manual for a detailed description of the debugger (dbx).

For information on the interface to programs written in assembly language, refer to the Assembly Language Programmer's Guide.

Organization of Information

This manual contains the following chapters and appendix:

Typographical Conventions

The following conventions and symbols are used in the text to describe the form of Fortran statements:


Indicates literal command line options, filenames, keywords, function/subroutine names, pathnames, and directory names.


Represents user-defined values. Replace the item in italics with a legal value. Italics are also used for command names, manual page names, and manual titles.


Indicates command syntax, program listings, computer output, and error messages.

Courier bold 

Indicates user input.

[ ] 

Enclose optional command arguments.


Surround arguments or are empty if the function has no arguments following function/subroutine names. Surround manual page section in which the command is described following IRIX commands.


Ssparates two or more optional items.


Indicates that the preceding optional items can appear more than once in succession.


IRIX shell prompt for the superuser.


IRIX shell prompt for users other than superuser.

Here are two examples illustrating the syntax conventions.

DIMENSION a(d) [,a(d)] ...  

indicates that the Fortran keyword DIMENSION must be written as shown, that the user-defined entity a(d) is required, and that one or more of a(d) can be optionally specified. Note that the pair of parentheses ( ) enclosing d is required.

{STATIC | AUTOMATIC} v [,v] ... 

indicates that either the STATIC or AUTOMATIC keyword must be written as shown, that the user-defined entity v is required, and that one or more of v items can be optionally specified.