This manual provides information on implementing Fortran 77 programs using IRIX™ and the IRIS®-4D™ series workstation. This implementation of Fortran 77 contains full American National Standard (ANSI) Programming Language Institute Fortran (X3.9–1978). Extensions provide full VMS Fortran compatibility to the extent possible without the VMS operating system or VAX data representation. This implementation of Fortran 77 also contains extensions that provide partial compatibility with programs written in SVS Fortran and Fortran 66.

Fortran 77 is referred to as “Fortran” throughout this manual except where distinctions between Fortran 77 and Fortran 66 are being specifically discussed.

Corequisite Publications

Refer to the Fortran 77 Language Reference Manual for a description of the Fortran language as implemented by the Silicon Graphics® IRIS-4D series workstation.

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

  • an overview of the compiler system

  • improving program performance by using the profiling and optimization facilities of the compiler system

  • the dump utilities, archiver, and other tools used to maintain Fortran programs

Refer to the dbx Reference Manual for a detailed description of the debugger. For information on interfaces 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.


Sseparates 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.