Preface

Fortran Programming Guide

Preface

This guide presents the essential information programmers need to develop efficient applications using the Sun WorkShop^TM Fortran compilers, f77 (Fortran 77) and f95 (Fortran 95). It presents issues relating to input/output, program development, use and creation of software libraries, program analysis and debugging, numerical accuracy, porting, performance, optimization, parallelization, and the C/Fortran interface.

Discussion of the compiler command-line options and their use can be found in the companion book, the Fortran User's Guide.

This guide is intended for scientists, engineers, and programmers who have a working knowledge of the Fortran language and wish to learn how to use the Sun Fortran compilers effectively. Familiarity with the Solaris operating environment or UNIX^® in general is also assumed.

Multiplatform Release

This Sun WorkShop Fortran release supports versions 2.6, 7, and 8 of the Solaris^TM SPARC^TM Platform Edition Operating Environment.

See the README files fortran_77 and fortran_95, in the Sun WorkShop READMEs directory for information regarding availability of this release of the f77 and f95 compilers on specific platforms. (See page 16.)

Access to Sun WorkShop Development Tools

Because Sun WorkShop product components and man pages do not install into the standard /usr/bin/ and /usr/share/man directories, you must change your PATH and MANPATH environment variables to enable access to Sun WorkShop compilers and tools.

To determine if you need to set your PATH environment variable:
1. Display the current value of the PATH variable by typing:

% echo $PATH
2. Review the output for a string of paths containing /opt/SUNWspro/bin/.

If you find the paths, your PATH variable is already set to access Sun WorkShop development tools. If you do not find the paths, set your PATH environment variable by following the instructions in this section.

To determine if you need to set your MANPATH environment variable:
1. Request the workshop man page by typing:

% man workshop
2. Review the output, if any.

If the workshop(1) man page cannot be found or if the man page displayed is not for the current version of the software installed, follow the instructions in this section for setting your MANPATH environment variable.
Note – The information in this section assumes that your Sun WorkShop 6 products were installed in the /opt directory. Contact your system administrator if your Sun WorkShop software is not installed in /opt.

The PATH and MANPATH variables should be set in your home .cshrc file if you are using the C shell or in your home .profile file if you are using the Bourne or Korn shells:

To use Sun WorkShop commands, add the following to your PATH variable:

/opt/SUNWspro/bin

To access Sun WorkShop man pages with the man command, add the following to your MANPATH variable:

/opt/SUNWspro/man

For more information about the PATH variable, see the csh(1), sh(1), and ksh(1) man pages. For more information about the MANPATH variable, see the man(1) man page. For more information about setting your PATH and MANPATH variables to access this release, see the Sun WorkShop 6 Installation Guide or your system administrator.

How This Book Is Organized

Chapter 1, "Introduction," briefly describes the features of the compilers.

Chapter 2, "Fortran Input/Output," discusses how to use I/O efficiently.

Chapter 3, "Program Development," demonstrates how program management tools like SCCS, make, and Teamware can be helpful.

Chapter 4, "Libraries," explains use and creation of software libraries.

Chapter 5, "Program Analysis and Debugging," describes use of dbx and other analysis tools.

Chapter 6, "Floating-Point Arithmetic," introduces important issues regarding numerical computation accuracy.

Chapter 7, "Porting,"considers porting programs to Sun compilers.

Chapter 8, "Performance Profiling," describes techniques for performance measurement.

Chapter 9, "Performance and Optimization," indicates ways to improve execution performance of Fortran programs.

Chapter 10, "SPARC: Parallelization," explains the multiprocessing features of the compilers.

Chapter 11, "C-Fortran Interface," describes how C and Fortran routines can call each other and pass data.

Typographic Conventions

TABLE P-1 shows the typographic conventions that are used in Sun WorkShop documentation.
TABLE P-1 Typographic Conventions Typeface Meaning Examples AaBbCc123 The names of commands, files, and directories; on-screen computer output Edit your .login file. Use ls -a to list all files. % You have mail. AaBbCc123 What you type, when contrasted with on-screen computer output % su Password: AaBbCc123 Book titles, new words or terms, words to be emphasized Read Chapter 6 in the User's Guide. These are called class options. You must be superuser to do this. AaBbCc123 Command-line placeholder text; replace with a real name or value To delete a file, type rm filename.
The symbol stands for a blank space where a blank is significant:

36.001
FORTRAN 77 examples appear in tab format, while Fortran 95 examples appear in free format. Examples common to both Fortran 77 and 95 use tab format except where indicated.
The FORTRAN 77 standard uses an older convention of spelling the name "FORTRAN" capitalized. Sun documentation uses both FORTRAN and Fortran. The current convention is to use lower case: "Fortran 95".
References to online man pages appear with the topic name and section number. For example, a reference to GETENV will appear as getenv(3F), implying that the man command to access this page would be: man -s 3F getenv
System Administrators may install the Sun WorkShop Fortran compilers and supporting material at: <install_point>/SUNWspro/ where <install_point> is usually /opt for a standard install. This is the location assumed in this book.
Shell Prompts

TABLE P-2 shows the default system prompt and superuser prompt for the C shell, Bourne shell, and Korn shell.

TABLE P-2   Shell Prompts
Shell Prompt

C shell %

Bourne shell and Korn shell $

C shell, Bourne shell, and Korn shell superuser #

Related Documentation

You can access documentation related to the subject matter of this book in the following ways:

Through the Internet at the docs.sun.com^sm Web site. You can search for a specific book title or you can browse by subject, document collection, or product at the following Web site:

http://docs.sun.com

Through the installed Sun WorkShop products on your local system or network. Sun WorkShop 6 HTML documents (manuals, online help, man pages, component readme files, and release notes) are available with your installed Sun WorkShop 6 products. To access the HTML documentation, do one of the following:

In any Sun WorkShop or Sun WorkShop^TM TeamWare window, choose Help About Documentation.
In your Netscape^TM Communicator 4.0 or compatible version browser, open the following file:

/opt/SUNWspro/docs/index.html

(Contact your system administrator if your Sun WorkShop software is not installed in the /opt directory.) Your browser displays an index of Sun WorkShop 6 HTML documents. To open a document in the index, click the document's title.

TABLE P-3 lists related Sun WorkShop 6 manuals by document collection.

TABLE P-3   Related Sun WorkShop 6 Documentation by Document Collection
Document Collection Document Title Description

Forte^TM Developer 6 / Sun WorkShop 6 Release Documents About Sun WorkShop 6 Documentation Describes the documentation available with this Sun WorkShop release and how to access it.

What's New in Sun WorkShop 6 Provides information about the new features in the current and previous release of Sun WorkShop.

Sun WorkShop 6 Release Notes Contains installation details and other information that was not available until immediately before the final release of Sun WorkShop 6. This document complements the information that is available in the component readme files.

Forte Developer 6 / Sun WorkShop 6 Analyzing Program Performance With Sun WorkShop 6 Explains how to use the new Sampling Collector and Sampling Analyzer (with examples and a discussion of advanced profiling topics) and includes information about the command-line analysis tool er_print, the LoopTool and LoopReport utilities, and UNIX profiling tools prof, gprof, and tcov.

Debugging a Program With dbx Provides information on using dbx commands to debug a program with references to how the same debugging operations can be performed using the Sun WorkShop Debugging window.

Introduction to Sun WorkShop Acquaints you with the basic program development features of the Sun WorkShop integrated programming environment.

Forte^TM C 6 / Sun WorkShop 6 Compilers C C User's Guide Describes the C compiler options, Sun-specific capabilities such as pragmas, the lint tool, parallelization, migration to a 64-bit operating system, and ANSI/ISO-compliant C.

Forte^TM C++ 6 / Sun WorkShop 6 Compilers C++ C++ Library Reference Describes the C++ libraries, including C++ Standard Library, Tools.h++ class library, Sun WorkShop Memory Monitor, Iostream, and Complex.

C++ Migration Guide Provides guidance on migrating code to this version of the Sun WorkShop C++ compiler.

C++ Programming Guide Explains how to use the new features to write more efficient programs and covers templates, exception handling, runtime type identification, cast operations, performance, and multithreaded programs.

C++ User's Guide Provides information on command-line options and how to use the compiler.

Sun WorkShop Memory Monitor User's Manual Describes how the Sun WorkShop Memory Monitor solves the problems of memory management in C and C++. This manual is only available through your installed product (see /opt/SUNWspro/docs/index.html) and not at the docs.sun.com Web site.

Forte^TM for High Performance Computing 6 / Sun WorkShop 6 Compilers Fortran 77/95 Fortran Library Reference Provides details about the library routines supplied with the Fortran compiler.

Fortran Programming Guide Discusses issues relating to input/output, libraries, program analysis, debugging, and performance.

Fortran User's Guide Provides information on command-line options and how to use the compilers.

FORTRAN 77 Language Reference Provides a complete language reference.

Interval Arithmetic Programming Reference Describes the intrinsic INTERVAL data type supported by the Fortran 95 compiler.

Forte^TM TeamWare 6 / Sun WorkShop TeamWare 6 Sun WorkShop TeamWare 6 User's Guide Describes how to use the Sun WorkShop TeamWare code management tools.

Forte Developer 6/ Sun WorkShop Visual 6 Sun WorkShop Visual User's Guide Describes how to use Visual to create C++ and Java^TM graphical user interfaces.

Forte^TM / Sun Performance Library 6 Sun Performance Library Reference Discusses the optimized library of subroutines and functions used to perform computational linear algebra and fast Fourier transforms.

Sun Performance Library User's Guide Describes how to use the Sun-specific features of the Sun Performance Library, which is a collection of subroutines and functions used to solve linear algebra problems.

Numerical Computation Guide Numerical Computation Guide Describes issues regarding the numerical accuracy of floating-point computations.

Standard Library 2 Standard C++ Class Library Reference Provides details on the Standard C++ Library.

Standard C++ Library User's Guide Describes how to use the Standard C++ Library.

Tools.h++ 7 Tools.h++ Class Library Reference Provides details on the Tools.h++ class library.

Tools.h++ User's Guide Discusses use of the C++ classes for enhancing the efficiency of your programs.

TABLE P-4 describes related Solaris documentation available through the docs.sun.com Web site.

TABLE P-4   Related Solaris Documentation
Document Collection Document Title Description

Solaris Software Developer Linker and Libraries Guide Describes the operations of the Solaris link-editor and runtime linker and the objects on which they operate.

Programming Utilities Guide Provides information for developers about the special built-in programming tools that are available in the Solaris operating environment.

`%` `echo $PATH`

`%` `man workshop`

**TABLE P-1** Typographic Conventions
Typeface	Meaning	Examples
`AaBbCc123`	The names of commands, files, and directories; on-screen computer output	Edit your `.login` file. Use `ls -a` to list all files. `% You have mail`.
`AaBbCc123`	What you type, when contrasted with on-screen computer output	`%` `suPassword:`
AaBbCc123	Book titles, new words or terms, words to be emphasized	Read Chapter 6 in the User's Guide. These are called class options. You must be superuser to do this.
AaBbCc123	Command-line placeholder text; replace with a real name or value	To delete a file, type `rm` filename.

36.001

**TABLE P-2** Shell Prompts
Shell	Prompt
C shell	`%`
Bourne shell and Korn shell	`$`
C shell, Bourne shell, and Korn shell superuser	`#`

**TABLE P-3** Related Sun WorkShop 6 Documentation by Document Collection
Document Collection	Document Title	Description
Forte^TM Developer 6 / Sun WorkShop 6 Release Documents	About Sun WorkShop 6 Documentation	Describes the documentation available with this Sun WorkShop release and how to access it.
	What's New in Sun WorkShop 6	Provides information about the new features in the current and previous release of Sun WorkShop.
	Sun WorkShop 6 Release Notes	Contains installation details and other information that was not available until immediately before the final release of Sun WorkShop 6. This document complements the information that is available in the component readme files.
Forte Developer 6 / Sun WorkShop 6	Analyzing Program Performance With Sun WorkShop 6	Explains how to use the new Sampling Collector and Sampling Analyzer (with examples and a discussion of advanced profiling topics) and includes information about the command-line analysis tool `er_print`, the LoopTool and LoopReport utilities, and UNIX profiling tools `prof`, `gprof`, and `tcov`.
	Debugging a Program With dbx	Provides information on using dbx commands to debug a program with references to how the same debugging operations can be performed using the Sun WorkShop Debugging window.
	Introduction to Sun WorkShop	Acquaints you with the basic program development features of the Sun WorkShop integrated programming environment.
Forte^TM C 6 / Sun WorkShop 6 Compilers C	C User's Guide	Describes the C compiler options, Sun-specific capabilities such as pragmas, the `lint` tool, parallelization, migration to a 64-bit operating system, and ANSI/ISO-compliant C.
Forte^TM C++ 6 / Sun WorkShop 6 Compilers C++	C++ Library Reference	Describes the C++ libraries, including C++ Standard Library, Tools.h++ class library, Sun WorkShop Memory Monitor, Iostream, and Complex.
	C++ Migration Guide	Provides guidance on migrating code to this version of the Sun WorkShop C++ compiler.
	C++ Programming Guide	Explains how to use the new features to write more efficient programs and covers templates, exception handling, runtime type identification, cast operations, performance, and multithreaded programs.
	C++ User's Guide	Provides information on command-line options and how to use the compiler.
	Sun WorkShop Memory Monitor User's Manual	Describes how the Sun WorkShop Memory Monitor solves the problems of memory management in C and C++. This manual is only available through your installed product (see `/opt/SUNWspro/docs/index.html`) and not at the `docs.sun.com` Web site.
Forte^TM for High Performance Computing 6 / Sun WorkShop 6 Compilers Fortran 77/95	Fortran Library Reference	Provides details about the library routines supplied with the Fortran compiler.
	Fortran Programming Guide	Discusses issues relating to input/output, libraries, program analysis, debugging, and performance.
	Fortran User's Guide	Provides information on command-line options and how to use the compilers.
	FORTRAN 77 Language Reference	Provides a complete language reference.
	Interval Arithmetic Programming Reference	Describes the intrinsic `INTERVAL` data type supported by the Fortran 95 compiler.
Forte^TM TeamWare 6 / Sun WorkShop TeamWare 6	Sun WorkShop TeamWare 6 User's Guide	Describes how to use the Sun WorkShop TeamWare code management tools.
Forte Developer 6/ Sun WorkShop Visual 6	Sun WorkShop Visual User's Guide	Describes how to use Visual to create C++ and Java^TM graphical user interfaces.
Forte^TM / Sun Performance Library 6	Sun Performance Library Reference	Discusses the optimized library of subroutines and functions used to perform computational linear algebra and fast Fourier transforms.
	Sun Performance Library User's Guide	Describes how to use the Sun-specific features of the Sun Performance Library, which is a collection of subroutines and functions used to solve linear algebra problems.
Numerical Computation Guide	Numerical Computation Guide	Describes issues regarding the numerical accuracy of floating-point computations.
Standard Library 2	Standard C++ Class Library Reference	Provides details on the Standard C++ Library.
	Standard C++ Library User's Guide	Describes how to use the Standard C++ Library.
Tools.h++ 7	Tools.h++ Class Library Reference	Provides details on the `Tools.h++` class library.
	Tools.h++ User's Guide	Discusses use of the C++ classes for enhancing the efficiency of your programs.

**TABLE P-4** Related Solaris Documentation
Document Collection	Document Title	Description
Solaris Software Developer	Linker and Libraries Guide	Describes the operations of the Solaris link-editor and runtime linker and the objects on which they operate.
	Programming Utilities Guide	Provides information for developers about the special built-in programming tools that are available in the Solaris operating environment.

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