FORTRAN 77 Language Reference FORTRAN 77 Version 5.0 901 San Antonio Road Palo Alto, , CA 94303-4900 USA 650 960-1300 fax 650 969-9131 Part No: 805-4939 Revision A, February 1999 Copyright Copyright 1999 Sun Microsystems, Inc. 901 San Antonio Road, Palo Alto, California 94303-4900 U.S.A. All rights reserved. All rights reserved. This product or document is protected by copyright and distributed under licenses restricting its use, copying, distribution, and decompilation. No part of this product or document may be reproduced in any form by any means without prior written authorization of Sun and its licensors, if any. Portions of this product may be derived from the UNIX® system, licensed from Novell, Inc., and from the Berkeley 4.3 BSD system, licensed from the University of California. UNIX is a registered trademark in the United States and in other countries and is exclusively licensed by X/Open Company Ltd. 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CETTE PUBLICATION EST FOURNIE "EN L’ETAT" SANS GARANTIE D’AUCUNE SORTE, NI EXPRESSE NI IMPLICITE, Y COMPRIS, ET SANS QUE CETTE LISTE NE SOIT LIMITATIVE, DES GARANTIES CONCERNANT LA VALEUR MARCHANDE, L’APTITUDE DES PRODUITS A REPONDRE A UNE UTILISATION PARTICULIERE OU LE FAIT QU’ILS NE SOIENT PAS CONTREFAISANTS DE PRODUITS DE TIERS. Please Recycle Contents Preface xix 1. Elements of FORTRAN 1 Standards Conformance 1 Extensions 2 Basic Terms 2 Character Set 2 Symbolic Names 4 Program Units 6 Statements 7 Executable and Nonexecutable Statements 7 FORTRAN Statements 7 Source Line Formats 8 Standard Fixed Format 9 Tab-Format 9 Mixing Formats 9 Continuation Lines 9 Extended Lines 10 Padding 10 Comments and Blank Lines 10 Contents iii Directives 11 2. Data Types and Data Items 13 Types 13 Rules for Data Typing 13 Array Elements 14 Functions 14 Properties of Data Types 15 Size and Alignment of Data Types 20 Constants 24 Character Constants 24 Complex Constants 27 COMPLEX*16 Constants 27 COMPLEX*32 (Quad Complex) Constants 27 Integer Constants 28 Logical Constants 29 Real Constants 29 REAL*8 (Double-Precision Real) Constants 31 REAL*16 (Quad Real) Constants 32 Typeless Constants (Binary, Octal, Hexadecimal) 32 Fortran 90-Style Constants @ 36 Variables 36 Arrays 37 Array Declarators 37 Array Names with No Subscripts 40 Array Subscripts 40 Array Ordering 42 Substrings 43 Structures 45 iv FORTRAN 77 Language Reference ♦ Revision A, February 1999 Syntax 45 Field Declaration 45 Rules and Restrictions for Structures 46 Rules and Restrictions for Fields 46 Record Declaration 47 Record and Field Reference 48 Substructure Declaration 49 Unions and Maps 50 Pointers 52 Syntax Rules 52 Usage of Pointers 53 Address and Memory 53 Optimization and Pointers 55 3. Expressions 59 Expressions, Operators, and Operands 59 Arithmetic Expressions 60 Basic Arithmetic Expressions 61 Mixed Mode 62 Arithmetic Assignment 65 Character Expressions 66 Character String Assignment 67 Rules of Assignment 69 Logical Expressions 69 Relational Operator 72 Constant Expressions 73 Record Assignment 74 Evaluation of Expressions 75 4. Statements 77 Contents v ACCEPT 77 Description 78 ASSIGN 78 Description 78 Restrictions 78 Examples 79 Assignment 79 Description 80 Examples 82 AUTOMATIC 84 Description 84 Restrictions 84 Examples 85 Restrictions 85 BACKSPACE 85 Description 86 Examples 86 BLOCK DATA 87 Description 87 Restrictions 88 Example 88 BYTE 88 Description 89 Example 89 CALL 89 Description 89 Examples 91 CHARACTER 92 vi FORTRAN 77 Language Reference ♦ Revision A, February 1999 Description 93 Examples 93 CLOSE 95 Description 95 Comments 96 Examples 96 COMMON 97 Description 97 Restrictions 97 Examples 98 COMPLEX 98 Description 99 Comments 100 Examples 100 CONTINUE 101 Description 101 Example 101 DATA 102 Description 102 Examples 104 DECODE/ENCODE 105 Description 105 Example 106 DIMENSION 107 Description 107 Examples 108 DO 109 Description 110 Contents vii Restrictions 112 Comments 112 Examples 112 DO WHILE 113 Description 114 Restrictions 115 Comments 115 Examples 116 DOUBLE COMPLEX 116 Description 116 Comments 117 DOUBLE PRECISION 117 Description 118 Example 118 ELSE 118 Description 119 Restrictions 119 Examples 119 ELSE IF 120 Description 120 Restrictions 121 Example 121 ENCODE/DECODE 121 Description 122 Example 122 END 122 Description 122 Example 123 viii FORTRAN 77 Language Reference ♦ Revision A, February 1999 END DO 123 Description 123 Examples 123 END FILE 124 Description 124 Restrictions 125 Examples 125 END IF 125 Description 126 Examples 126 END MAP 126 Description 126 Restrictions 126 Example 127 END STRUCTURE 127 Description 127 Example 127 END UNION 127 Description 128 Example 128 ENTRY 128 Description 128 Restrictions 129 Examples 129 EQUIVALENCE 130 Description 131 Restrictions 131 Example 132 Contents ix EXTERNAL 132 Description 133 Restrictions 133 Examples 133 FORMAT 134 Description 136 Restrictions 137 Warnings 137 Examples 137 FUNCTION (External) 138 Description 140 Restrictions 141 Examples 141 GO TO (Assigned) 142 Description 142 Restrictions 143 Example 143 GO TO (Computed) 143 Description 144 Restrictions 144 Example 144 GO TO (Unconditional) 145 Description 145 Restrictions 145 Example 145 IF (Arithmetic) 145 Description 146 Example 146 x FORTRAN 77 Language Reference ♦ Revision A, February 1999 IF (Block) 146 Description 147 Restrictions 148 Examples 148 IF (Logical) 149 Description 149 Example 150 IMPLICIT 150 Description 152 Restrictions 152 Examples 153 INCLUDE 154 Description 154 Examples 155 INQUIRE 156 Description 157 Examples 162 INTEGER 163 Description 163 Restrictions 164 Examples 164 INTRINSIC 164 Description 165 Restrictions 165 LOGICAL 166 Description 167 Examples 168 MAP 168 Contents xi Description 168 Example 169 NAMELIST 169 Description 169 Restrictions 170 Example 170 OPEN 171 Description 171 Examples 176 OPTIONS 178 Description 178 Restrictions 179 Example