Fortran 90 Handbook - USTC

1 Fortran 90 HandbookComplete ANSI / ISO ReferenceJeanne C. AdamsWalter S. BrainerdJeanne T. MartinBrian T. SmithJerrold L. WagenerIntertext PublicationsMcGraw-Hill Book CompanyLibrary of Congress Catalog Card Number 91-77211 Copyright 1992 by Jeanne C. Adams, Walter S. Brainerd, Jeanne T. Martin, Brian T. Smith, and Jerrold L. Wagener. All rightsreserved. Printed in the United States of America. Except as permitted under the United States Copyright Act of 1976, no part ofthis book may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system without theprior written permission of the authors and the 9 8 7 6 5 4 3 2 1 ISBN 0-07-000406-4 Intertext Publications/Multiscience Press, Inc. One Lincoln Plaza New York, NY 10023 McGraw-Hill Book Company 1221 Avenue of the Americas New York, NY 10020 Composition by UNICOMPiiiPrefaceTheFortran 90 Handbook is a definitive and comprehensive guide to Fortran 90and its use.

2 Fortran 90, the latest standard version of Fortran , has manyexcellent new features that will assist the programmer in writing efficient,portable, and maintainable programs. TheFortran 90 Handbook is an informaldescription of Fortran 90, developed to provide not only a readableexplanation of features, but also some rationale for the inclusion of featuresand their use. In addition, models give the reader better insight as to whythings are done as they are in the Handbook is intended for anyone who wants a comprehensive survey ofFortran 90, including those familiar with programming language concepts butunfamiliar with Fortran . Experienced Fortran 77 programmers will be able touse this volume to assimilate quickly those features in Fortran 90 that are notin Fortran 77 ( Fortran 90 is a superset of Fortran 77).Chapter 0 provides a brief overview of several of the most important featuresthat are new in Fortran 90.

3 Chapters 1 14 correspond to Sections 1 14 in thestandard. (The standard is the complete official description of the language,but it is written in a legally airtight, formal style without tutorial material andcan be difficult to understand in places.) The Handbook and the standard canbe examined in parallel for insights into the Fortran language. This makes itfeasible to use this Handbook to decipher the standard, and this is an idealuse of this the Handbook is written for use in conjunction with the standard, itis also designed as a practical stand-alone description of Fortran 90. In theinterest of readability, a few of the more obscure aspects of the standard mayivFORTRAN User s Guidenot be treated rigorously; any such cases should not impact the usefulness ofthis Handbook in describing Fortran 90. On the other hand, in places where thestandard is not completely clear, a reasonable interpretation is often given,together with ways to implement and program that will avoid potentialproblems due to misinterpretation of the standard.

4 Of course, if information isbeing sought to understand a fine point of compiler implementation, settle abet, resolve a court case, or determine the answer to a Fortran trivia question,the standard itself should be considered the final syntactic features of the language are described completely in theappendices, and these can serve as continual concise references for Fortran Sources of InformationOther parts of the book can be used to help find information. Each of the intrinsic functions is described in detail in Appendix A,although a general discussion of the intrinsic functions is included inChapter 13. The complete syntax of Fortran 90 may be found in Appendix B. The syntaxrules are numbered exactly as they are in the Fortran standard. There is across reference that lists, for each nonterminal syntactic term, the number ofthe rule in which it is defined, and all rules in which it is referenced.

5 Appendix C contains a listing of the obsolescent features. The index is unusually comprehensive. There is an index of examples, giving the location of program examples thatillustrate the use of many Fortran 90 an informal and tutorial approach to learning Fortran 90, the book,Programmers Guide to Fortran 90, Second Edition, by Brainerd, Goldberg, andAdams (Unicomp, Albuquerque, NM, 1993) is more of the Programming ExamplesIn order to illustrate many features of the language and as many uses of thesefeatures as possible, no single particular style has been used when writing theexamples. In many cases, the style illustrated is not necessarily one that theauthors in the appendices of this book was developed by the ANSI committeeX3J3 and the ISO committee SC22/WG5 for inclusion in the Fortran 90standard ISO/IEC 1539 : 1991. This material is reprinted with the permission ofthe International Standards provided by Charles Goldberg have increased the accuracy andreadability of this book 90 Handbook is reproduced herein with the permission of McGraw-Hill, Inc.

6 , Copyright 1992, by Walter S. Brainerd, Jeanne C. Adams, Jeanne , Brian T. Smith, and Jerrold L. Wagener. All rights CopiesPrinted copies of this book may be obtained by ordering fromUnicomp, San Bernardino Ave NEAlbuquerque, NM 87122 USA+1-505-275-0800+1-505-856-1501 (fax)Visit the Fortran market: home page includes how to order this book in hard C. AdamsWalter S. Brainerd, T. MartinBrian T. SmithJerrold L. WagenerJanuary 1992viFORTRAN User s GuideviiCopyright 1992 J. Adams, W. Brainerd, J. Martin, B. Smith, and J. WagenerTable of ContentsPreface..iiiSneak Preview ..11. Introduction .. History .. Why a New Standard? .. Why Not Use Another Language? .. Development of Fortran 90 .. Fortran 77 Compatibility .. Extensibility.. Intrinsic and Standard Modules .. The Fortran 90 Language Standard .. References ..242. Fortran Concepts and Terms .. Scope and Association.

7 Program Organization .. Data Environment .. Program Execution .. Terms .. Summary of Forms .. Ordering Requirements ..57viiiFortran 90 HandbookCopyright 1992 J. Adams, W. Brainerd, J. Martin, B. Smith, and J. Example Fortran 90 Program .. Summary ..593. Language Elementsand Source Form .. The Processor Character Set .. Lexical Tokens .. Source Form .. Rules for Fixed/Free Source Form .. The INCLUDE Line .. Low-Level Syntax .. Summary ..844. Data Types .. Building the Data Environment for a Problem Solution . What Is Meant by Type in Fortran ? .. Intrinsic Data Types .. Derived Types .. Structure Constructors .. Array Constructors.. Summary ..1275. Declarations .. Type Declaration Statements.. Implicit Typing .. Array Properties .. Pointer Properties .. Value Attributes .. Object Accessibility and Use.

8 Procedure Properties .. Automatic Data Objects .. NAMELIST Statement .. Storage Association .. Summary ..186 Table of ContentsixCopyright 1992 J. Adams, W. Brainerd, J. Martin, B. Smith, and J. Wagener6. Using Data .. Constants and Variables .. Substrings .. Structure Components .. Arrays .. Pointers and Allocatable Arrays .. Summary ..2227. Expressions and Assignment .. Introduction to Fortran 90 Expressions .. Formation of Expressions .. Interpretation of Expressions .. Evaluation of Expressions .. Assignment .. Summary ..3038. Controlling Execution .. The Execution Sequence .. Blocks and Executable Constructs .. IF Construct and IF Statement .. The CASE Construct.. The DO Construct.. Branching.. Obsolescent Control Statements .. Summary ..3419. Input and Output Processing .. Records, Files, Access Methods, and Units.

9 Data Transfer Statements .. Execution Model for Data Transfer Statements .. Error and Other Conditions in Input/Output Statements The OPEN Statement .. The CLOSE Statement .. Inquiring about Files .. File Positioning Statements ..417xFortran 90 HandbookCopyright 1992 J. Adams, W. Brainerd, J. Martin, B. Smith, and J. Restrictions: I/O Specifiers, List Items, and Statements . Summary ..42310. Input and Output Editing .. Explicit Formatting.. Format Specifications .. Character String Edit Descriptor Form .. Formatted Data Transfer .. File Positioning by Format Control .. Numeric Editing .. Logical Editing .. Character Editing .. Control Edit Descriptors .. List-Directed Formatting .. Namelist Formatting .. Summary ..48011. Program Units .. Overview .. Main Program .. Internal Procedures .. Host Association.

10 External Subprograms .. Modules .. Block Data Program Units .. Summary ..51612. Using Procedures .. Procedure Terms and Concepts .. Subroutines .. Functions .. Procedure-Related Statements .. Argument Association .. Procedure Interfaces.. Summary ..587 Table of ContentsxiCopyright 1992 J. Adams, W. Brainerd, J. Martin, B. Smith, and J. Wagener13. Intrinsic Procedures .. Intrinsic Procedure Terms and Concepts .. Representation Models .. Inquiry and Numeric Manipulation Functions .. Transfer and Conversion Functions .. Computation Functions .. Array Functions .. Intrinsic Subroutines .. Alphabetical List of All Intrinsic Procedures .. Specific Names for Generic Intrinsic Procedures .. Summary ..61514. Scope, Association, and Definition .. The Use of Names.. Scope .. Association .. Definition Status ..637A.