Intel fortran-80 User Manual

FORTRAN-SO

PROGRAMMING

MANUAL

Manual

Order

Number: 9800481 A

Copyright

Intel

I

Corporation,

3065 Bowers Avenue, Santa Clara,

Corporation

California

95051

. I

The information in this

document

is

subject to change without notice.

Corporation

Intel to, the implied warranties

makes

no

warranty

of

merchantability

of

assumes no responsibility for any errors commitment to

part

No written consent

The following are

and the combination

Additional copies

Literature Intel

update

of

this

document of

ICE iCS In

site Intel Intellec

Department

Corporation

nor

to keep current the

may be copied

Intel

Corporation.

trademarks

of

Intel

ICE, iCS, iSBC, MCS,

this

manual

Corporation

or

other

3065 Bowers A venue Santa Clara,

CA

95051

any kind with regard to this material, including,

and

that

or

fitness for a particular purpose. Intel

may

appear

information

reproduced in any form

iSBC Library MCS Megachassis Micromap Multibus

or

in this document. Intel

contained in this document.

or

by any means without the prior

and

may be used only

Manager

to

RMX and a numerical suffix.

describe

PROMPT Promware RMX UPI ",Scope

Corporation

Interproducts:

Intel literature may be obtained from:

but

not

limited

Corporation

makes no

ii

PRINTED

IN

U.S.A./A151/1279/5K

CP

This

manual

for

programming

ANSI

FORTRAN FORTRAN sions

of

FORTRAN

describes the Intel-developed

the 8080

77

full language;

and

8085 microcomputers.

subset. In some instances, it

FORTRAN-80

77.

FORTRAN

also has features

language (FORTRAN-80)

FORTRAN-80

incorporates

is

based

features from the

that

exceed

both

PREFACE

on

the

ver-

Appendix found features features are clearly not tability

The or

extensions related to a for operator's system environments (such as ISIS-II

The experienced reviewing the summaries in the appendixes should

programming

a Chapter

Chapter statements in detail. These statements lustrative examples. programming ing

as TRAN bibliography

D lists

in the

that

be used

among FORTRAN-80

that

compiler. They are summarized in Appendix F

read it

1 has a

2 introduces

a science. We also suggest

tutorials. Some recommended

FORTRAN-80

FORTRAN

go

beyond

if

you

processors.

manual

through

reference, it does contain some instructional material. short

techniques

at

the end

both

marked

want

to preserve total compatibility with

language

particular

also includes considerations when running in different

FORTRAN

from the beginning. While the

program

FORTRAN

Chapter

and

of

extensions to the

77

full set;

versions

in the text

is

described in its entirety in this

programmer

designed

7 suggests some guidelines for improving recommends sources for further study

that

Chapter

it

of

FORTRAN

of

this

compiler

and

RMX-80).

to

provide

concepts.

are

grouped

the beginning

introductory

7.

FORTRAN

also lists those

77. In

manual

are

can

of

Chapters

(shadowed in grey)

described in the

possibly begin

this

manual.

manual

an

intuitive feel for the language.

3-6 describe

functionally

programmer

texts

77 subset

FORTRAN-80

addition,

FORTRAN

manual.

operator's

of

this

programming

The

is

primarily written as

and

read

are

that

these superset

and

77

Limitations

manual.

new

programmer

FORTRAN-80

include

FORTRAN

of

programm-

one

included in the

can be

superset

should

and

por-

manual

The

operating

after

brief

two

FOR-

il-

Finally, all users necessary:

ISIS-II ISIS-II X3.9-1977

The latter

The 1430 Broadway New

10018

FORTRAN-80 System

American National

York, New York

User's

FORTRAN

document

of

this

Compiler

Guide

can

manual

Operator's

be

ordered

Standards

should refer to the following

Manual

from:

Institute, Inc.

documents

9800480 9800306

as

iii

PREF'ACE

GLOSSARY

CHAPTER 1 INTRODUCTION TO FORTRAN

1.1

An

Introductory

1.1.1

Comment

1.1.2 Type Statement

1.1.3

Input

1.1.4 Value Assignment Output

1.1.5

L 1.6

Program

1.2

Summary

1.2.1 Executable

1.2.2 Nonexecutable

1.2.3

Order

CHAPTER

2

Example

Lines

Statement

Statements. . . . . . . . . . . . . . . .

Termination.

Of

FORTRAN-SO

Statements.

of

Statements . . . . . . . . . . . . . .

................

....................

...................

..................

. . . . . . . . . . . .

Statements.

. . . . . . . . . . . .

Statements.

. . . . . . . . .

. . .

.. .. .. .. .. ..

FORTRAN CONCEPTS

2.1

FORTRAN

2.1.1

2.1.2

2.1.3 Statements

2.2

FORTRAN

2.2.1

2.2.2

2.2.3

2.2.4 Expressions

2.2.5 Scope Notational

2.3

CHAPTER

Program Program The

PROGRAM

Statement Character Constants Arrays

....................

of

Conventions . . . . . . . . . . . . . . .

Structure

units

and

Procedures

Statement

and

Lines. . . . . . . . . . . . . .

Elements.

Set.

.....................

and

Variables

and

Operators

Symbols

.................

.............

............

3

.........

..........

. . . . . . . . .

, . . . .

..........

.. ..

..

DEFINING VARIABLES, ARRA YS,AND MEMORY

3.1

TypeStatements

3.1.1

REAL

3.1.2

INTEGER

3.1.3

LOGICAL

3.1.4

CHARACTER

3.1.5

IMPLICIT

3.2

Array

Definition.

3.2.1

DIMENSION

3.2.2 Kinds

3.2.3 Properties

3.2.4 Referencing

3.3 Assignment Statements

3.3.1 Arithmetic Assignmnt 3,,3.2 Logical Assignment Statement.

3.3.3

Character

3.3.4

ASSIGN

3.3

.5

DATA

........................

Type

Statement

Type Statement . . . . . . . . .

Type Statement

Type

Statement

. . . . . . . . . . . . . . . . . . . . .

Statement

of

Array

Declarators

of

Arrays

Array

Assignment

Statement.

........

Statement.

..............

............

................

Elements . . . . . . . .

..................

Statement.

. . . . . . . . . . . . . .

. . . . . . . . . . . . . . .

,.....

..... , .....

. . . . .

..........

......

........

. . . .

..

.. ..

..

,

1-1 1-1

,

1-2

,

1-2 1-2 1-2 1-3 1-3 1-3 1-3 1-4

2-1 2-1

, 2-2

2-2 2-3

'2-3

, 2-4

2-6

, 2-7

2-12 2-13

3-1 3-1 3-1 3-2 3-3

, 3-3

3-4 , 3-5 , 3-5

3-6

3-6 , 3-7

3-S

3-9

3-10

CONTENTS I

3.4

Memory

3.4.1

3.4.2

3.4.3

3.4.4

CHAPTER

PROGRAM EXECUTION CONTROLS

4.1

Transferring

4.1.1 Unconditional

4.1.2

4.1.3 Assigned

4.1.4 Arithmetic

4.1.5 Logical

4.1.6

4.1.7 Block

4.1.S ELSE

4.1.9

4.1.10

4.2

Loop

4.2.1

4.2.2

4.2.3 Program

4.3

4.3.1

4.3.2

4.3.3

CHAPTERS FUNCTIONS

5.1 Intrinsic

5.1.1 Intrinsic Functions

5.1.2

5.1.3 Statement Functions

5.2 External Procedures

5.2.1

5.2.2 Subroutines

5.2.3

5.2.4 5 .2.5 SAVE

5.2.6

5.2.7

5.3 Arguments

5.3.1

5.3.2

5.3.3 Association

CHAPTER

INPUT/OUTPUT

6.1 Records, Files,

6.1.1 Record Properties

6.1.2 File Properties

6.1.3

Definition. EQUIVALENCE COMMON BLOCK BLOCK

. . . . . . . . . . . . . . . . . .

Statement

Statement DATA DATA

..............

Subprograms Statement

4

Program

Computer

IF

IF,

ELSE

IF IF

ELSE

Statement . . . . . . . . . . . . . . . . .

END

IF

Control

Operation DO CONTINUE

PAUSE STOP END

Statements . . . . . . . . . . . . . . .

Statement.

Termination

Statement.

Statement . . . . . . . . . . . . . . . . .

Statement

AND

And

Statement Functions . . . . . . . .

INTRINSIC

FUNCTION

SUBROUTINE

RETURN

Statement. EXTERNAL CALL

Statement.

And Common Dummy

and

Control

GO

TO

Statement

GO

TO

Statement.

GO

TO

Statement.

IF

Statement . . . . . . . . . . .

Statement.

IF,

and Statement Statement

Statement.

of a DO

Statement.

. . . . . . . . . . . . .

ELSE

.................

................

. . . . . . . . . . . . . .

Loop.

. . . . . . . . . . . . . . . . . .

Statements.

................

...................

SUBROUTINES

.................

Statement

...............

....................

Statement

......................

Statement.

Statement

Common

Blocks

Actual

of

...............

. . . . . . . . . . . . . . . .

Statement.

. . . . . . . . . . . . . . . .

Blocks Revisited

...................

Arguments.

Arguments

6

And

Units

.................

..................

....................

Unit

Properties.

. . . . . . . . . . . . . . . . .

.........

........

...........

.............

......

. . . . . . .

. . . . . . . .

Blocks

.......

. . . . . . . . . .

. . . . . . . . . . .

. . . . . . . .

.............

..............

...........

.............

. . . . .

............

..

3-11 3-11 3-12 3-13 3-14

4-1 4-1

..

4-1

..

4-2

..

4-2

..

4-3

, 4-3

4-4

, 4-4

..

4-5

..

4-5

..

4-6

..

4-6

..

4-6

..

4-7

..

4-7

,

4-S

..

4-S

,

4-S

..

5-1

5-1 , 5-2 , 5-2 , 5-4

5-4 , 5-5

5-6 , 5-6

..

5-7

..

5-S

... , 5-S

5-9

..

5-9

6-1

6-1 ,

6-1

..

6-3

v

6.2 File-Handling

6.2.1

OPEN CLOSE

6.2.2

6.2.3

BACKSPACE

6.2.4

REWIND

6.2.S

ENDFILE

6.3

Data-Transfer

6.3.1

READ

6.3.2

WRITEStatement PRINT

6.3.3 Formatted

6.4

6.4.1

Unformatted

6.4.2

Formatted

6.4.3

FORMAT

6.4.4 List-Directed

CHAPTER

Statement.

And

7

Statements.

Statement.

110

Statement

Unformatted

PROGRAMMING

7.1

Program

7.1.1

7.1.2

7.1.3 Refining the

7.1.4 Final Coding

7.2

FORTRAN

7.2.1 Functions

7.2.2

7.2.3 Crossing

7.2.4

7.2.S

7.3

References....

APPENDIX

FORTRAN-80

A.I

Statement Sequence

A.2 Statement

Development Problem Program

GO

Computing

Reminders........................

Coding.

TO

Statement

Definition.

Unit Lines

A

STATEMENT

Summary.

APPENDIXB INTRINSIC

B.l

Intrinsic Function

B.2 Notes On Intrinsic

FUNCTIONS

. . . . . . . . . . . . . .

. . . . . . . . . . . . . . . .

...............

Statement. . . . . . . . . . .

Statement

Statement.

Statements

Data

Statement

Formatting

.................

Data

Transfer.

...............

. . . . . . . . . . . .

.............

Data

Transfer..

.........

..........

...............

...........

GUIDELINES

.................

. . . . . . . . . . . . . .

Documentation.

Problem

....................

. . . . . . . . . . . . . . . . . . .

and

Subroutines . . . . . . . . .

..................

Variables

. . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . .

Definition.

...............

and

Constants. . ..

. . . .

SUMMARY

....................

. . . . . . . . . . . . . . . . . .

Summary.

Functions.

. . . . . . . . . . . .

. . . . . . . . . . .

.. .. " 6-8 ..

6-10

..

6-10 6-10 6-10 6-13 6-14 6-14 6-14

, 6-1S

6-16

, 6-22

" .. .. .. " .. ..

" 7-4

..

, A-I

..

.. ..

6-4 6-4

6-9

7-1 7-1 7-1 7-2 7-3 7-4 7-4 7-4

7-4

7-S 7-S

A-I

B-1 B-3

APPENDIX HOLLERITH

C.l

Hollerith As A

C.2

The Hollerith C.2.1 Hollerith

C.2.2

C.3 Hollerith C.4

'A'

APPENDIX EXTENSIONS

D.l

Standard

D.2

Nonstandard

D.3 More Specific Semantics

D.4 Differences

APPENDIX ASCII

CODES

APPENDIX 8080/8085

F.l

Processor Limitations

F.2

Compiler Extensions F .2.1 Lowercase Letters

F .2.2 F .2.3 Reentrant Procedures F .2.4 Free-form Line F.2.S F .2.6 Default F .2.7 Including Source Files F .2.8

F.2.9 Flexibility In

F.3

Unit Preconnection

C

DATA

Statements

Hollerith

Statements

Format

Editing

Of

TYPE

Data

Type. . . . . . . . . . . . . . .

Constant

Constants

......................

Constants

........................

Specification. . . . . . . . . . .

Hollerith

D

TO

ANSI

Extensions

Subset.

FORTRAN

FORTRAN.

. . . . . . . . . . . . . . . . . . . . . . . . .

From

To

Extensions

......................

. . . . . . . . . . . . . . . . . . . . .

1966

. . . . . . . . . . . . . . . . . . . . .

E

F

PROCESSOR

...................

Port

Input/Output.

Format.

Interpretation

RECL

Files. . . . . . . . . . . . . . . . . . . . . . . . . . . .

F.2.9.1 Association

Locations. F.2.9.2 Partially Initialized Arrays F.2.9.3 Transfers

of

Data

Lengths.

Specification

Standard

. . . . . . . . . . . . . . . . . . .

....................

INDEX

..................

In

DATA

In

CALL

Data.

. . . . . . . . . . .

FORTRAN

1977

To

1977

Than

1977

DEPENDENCIES

On

Language

................

. . . . . . . . . . . . . .

DO Statements

For

of

Memory

Into

An

.......

.............

. . . . . . . . . . .

.....

. . . . . . . . . . . .

.............

Sequential

Restrictions

....

IF Block

....

...

..

C-I C-l

"

C-l

..

C-2.

..

C-2

..

D-l

" D-l

..

0-2

..

0-2

" F-l "

F-l " F-2 ..

F-2 " F-2 ..

F-2 " F-3 ..

F-3 " F-3

..

F-4 " F-4

..

F-4 " F-4 " F-4 " F-4

1-1 1-2 2-1 2-2 Type, Length,

vi

Batting Average

Order

of

FORTRAN

Program

Units

(OPI +OP2)

Program

.......................

and

......................

...............

Statements

Interpretation

.........

of

1-1 1-4

2-1

2-8

ILLUSTRATIONS I

2-3 Type, Length,

(OPI **OP2) 2-4 3-1 3-2

Length Subscript Result

of(OPI . OR.

of

Value.

'v = e'

and

Interpretation

....................

OP2)

. . . . . . . . . . . . . . . . . . .

......................

of

.............

" 2-8

2-11

..

3-7 3-8

GLOSSARY

Argument(s) - A collection

formed. are

Array

selectively (by

Array

Association -

symbols.

tuals

of

are

Common

units.

Compiler -

executable

Equivalenced Expression - A

arithmetic,

File - A collection

ternal

quentially

Functions

replaced

with actual values

-

An

ordered

array

Element -

May

Association

when a procedure

memory

also said

by

to

two

be

Memory

The

software

form.

Memory

character,

(a

character

or

directly.

and

subroutines

set

of

element

An

individual

refer

to

of

arguments

is

referenced.

or

more

associated.

-

Memory

tool

-

Memory

combination

relational,

of

data

variable

of

values

when

data

that

name).

item within

association

items.

shared

for

of

logical,

records.

or

character

and

are

usually

the

functions

can

be

of

is

the

replacement

Association

The

symbol

by items in

translating

shared

by items in

operands,

or

May

be array

variables

defined

or

referenced

an

array.

arguments,

of

names

FORTRAN

operators,

Boolean.

external

element).

on

which a with

subroutines

collectively (by

of

dummy

memory

of

the

same

the

same

(any

Records

computation

dummy

memory

arguments

locations

the

items

or

source

and

ISIS-recognized file)

code

program

parentheses.

can

arguments

are

referenced.

array

locations,

is

the

sharing

different

into

units.

be accessed se-

is

per-

that

name)

or

of

with ac-

sharing

memory

program

machine-

May

be

or

in-

Function - A

Functions

ed. defined, program).

Length

two,

or

Character

routine

single-statement

of

Data -

four

bytes

data

Main Program -

gram

to

be

invoked. DATA first

Number

decimal,

Procedure -

SUBROUTINE

Program -

programs trollines,

statement

statement.

Base -

or

hexadecimal.

The

(FUNCTION,

library

Another

that

are

called

The

number

for

integer

occupies

The

subprograms

entire

procedures,

one

The

main

It

may

as its first

representation

term

executable

SUBROUTINE,

returns

a value

'intrinsic'

function),

of

bytes

and

byte

per

program

not

have a FUNCTION,

statement.

for a function

are

called

program

and

included

to

the

(FORTRAN

or

'external'

occupied

logical items

character.

is

the

first

It

may

used

for

numeric

'external'

includes BLOCK files.

calling

have a PROGRAM

statement

predefined),

(user-defined

by a

data

and

four

part

of

an

SUBROUTINE,

data.

or

subroutine.

procedures.

the

DATA)

when

item.

bytes

entire

May

main

plus

it

is

referenc'statement' FUNCTION

This

can

for

real items.

FORTRAN

or

statement

be

binary,

FUNCTION

program, any

compiler

(user-

sub-

be

one,

pro-

BLOCK

as its

octal,

and

all sub-

con-

vii

Glossary

FORTRAN-SO

Program Unit -

unit

must

Record

- A

Statement - A

pressions,

Statement

be

given a

Another

be

terminated

sequence

etc. A

statement

Label-

symbolic

of

A 1-5 digit

name

Subprogram - A tJlock

DA

T A

statement

Subroutine - A

SUBROUTINE the

last.

Unit - A logical

as its first

group

statement

way

of

name

by

an

values

of

syntactic

has

by

of

code

of

statements

mllst

referring

for a main

END

or

characters.

an

'initial'

integer

the

ASSIGN

having a FUNCTION,

statement

be

to

program

statement.

items:

statement

line

in

columns

statement.

and

the

for

performing a frequently-used

the

first

a file.

Once

or a subprogram.

label,

and

up

1-5

of a statement's

END

statement

statement;

connected,

keyword,

to

nine

'continuation'

SUBROUTINE,

as

its

the

END

statement

it

is

the

Every

arguments,

initial line.

last

statement.

operation.

same

as a file.

program

lines.

or

BLOCK

must

ex-

Can

The

be

viii

This

chapter TRAN also includes a quence.

1.1

An Introductory Example

A

FORTRAN processing the drawn statements

The

example calculates a baseball

opens

with a

a feel

for

the language.

summary

program

data

received,

from the statistical world

for doing these

short

The

of

FORTRAN-80

generally

and

operations.

CHAPTER

11

INTRODUCTION TO FORTRAN

example intended

example

performs

returning

of

the

player's

is statements

three basic

output.

sports

batting

to

give the newcomer

discussed in some d.etail.

and

their

proper

operations:

The

following

fan(atic), shows typical

average using the

receiving

short

equation:

to

FOR-

The

chapter

coding se-

input,

program,

FORTRAN

AVERAGE =

The

baseball statistician, sitting

how

often the is

done

he has

player's

only once.

name

batted, and

and

batting

TIMES AT BAT

at

his console terminal, enters the

his

total

average.

1.1.1 Comment Lines

The

first seven lines

document a program.

A

comment

any

characters blank line sent in line 7

line

is

considered a of

C CALCULATE BATTING AVERAGES C VARIABLES C PNAME = PLAYER'S C AB = TIMES AT BAT CHITS C AVG

C

CHARACTER*12 PNAME

10

20

of

the

example

must

have the letter

accepted by

the example.

FORTRAN

comment

Comment

USED-

= TOTAL BASE HITS

= BATTING AVERAGE

READ FORMAT AVG PRINT 20, FORMAT (A, 5X, F4.3) END

10, PNAME, AB, HITS

(A,

2(2X, F3.0))

= HITS/AB

PNAME, AVG

HITS

hits. To

are

comment

.

'C'

or

in the

line also.

lines have

NAME

name

of

a player,

The

program

keep this example simple, the calculation

lines.

an

asterisk (*) in

remainder

For

example, the

no

Comment

effect

returns

of

on

a listing showing

lines

are

used

column

the line. A completely

program

'C'

need

1 followed by

not

execution.

to

be pre-

Fig. 1-1 Batting Average

Program

1-1

Introduction

To

FORTRAN

1.1.2 Type Statement

FORTRAN-SO

Every variable used in a character, PNAME

No type statement FORTRAN be used

or

Hollerith. The

represents character

variable-naming convention tells us implicitly

to

name real data. This convention

FORTRAN

CHARACTER data

is

needed for the other variables listed (AB, HITS, AVO). The

program has a type - integer, real, logical,

and

may have up to

is

type statement says

12

characters.

that

described later in section 2.2.2.1.

that

these variables are to

1.1.3 Input Statements

Following the The first tells the program to read input data; the second describes the input

data.

The

number found in statement 10. The rest be specified by the person

CHARACTER

10

in the

READ

statement in the example are two input statements.

statement tells the

of

the statement lists the variables whose values will

at

the console.

By

program

that

the input format

default,thein,pu(is reaclfrOl11tbecori-

soleierlllinaL

The

FORMAT to

expect.

having the length

2X, F3.0, 2X, F3.0

and

refers followed by a 3-digit floating-point (F) number whose decimal digits. Clearly, no

statement (labeled statement

'A'

indicates the first field

of

to

the AB and

batter

PNAME,

the player's name. '2(2X, F3.0)'

HIT

comes to the plate 79.3 times

fields.

of

10)

tells the program what kind

data

is

a string

'2X'

indicates two blanks will be entered

of

alphanumeric characters

is

equivalent to

portion

or

has 22.8 hits.

the variable

format

of

contains

data

the

is

'0'

One might ask that

is,

2(2X,13}

The

reason by another. Since AB batting

1.000.

is

at

that

this point why

FORTRAN

~

truncates the remainder when one integer

HITS,

we

didn't

specify these fields

all averages would be

'0'

except for the rare player

1.1.4 Value Assignment Statement

The actual batting average calculation

AVG = HITS/AB

This

is

one form

ed the value

of

assignment statement, in which the

of

the expression

'HITS/

is

done by the next statement:

variable'

AB.'

1.1.5 Output Statements

Following the calculation are two

output

In the

~t~teI11e~t?O:'.flN~¥.E'~nd'AV9'

Qefa;tllt~.theoutpqtis~xi~t~n.

data; the next describes the

PRINT

statement, the

output

format

number

~qtheconsoJe.

lines. The first tells the

of

the

output.

20 indicates

are the items whose values are

that

the

output

to

be 'integer' data;

is

divided

AVO'

is

assign-

program

format

to

is

found in

be printed.

write

lly

1-2

FORTRAN-SO

Introduction

To

FORTRAN

Statement of

characters will be followed by five 'A

VG' decimal

20,

the

FORMAT

of

variable

field consists

digits.

statement,

length, as in

blanks

(5X)

of

four

floating-point

1.1.6 Program Termination

The

final

statement

the

FORTRAN

unit

must

be

terminated

1.2 Summary Of

The

statements classifications. and

some

from statements chapter

Statements do

calculations, ecutable units.

are

references

are

statements

terminates

compiler

by

that

an

the

it

hasTeached

END

FORTRAN·SO

available

These

the

listed in

are

classified as executable

read

in

FORTRAN-80

include all

FORTRAN

the

same

to

this

or

write

define

the

statements

sequence

manual,

110

characteristics

indicates

the

FORMAT

and

then

program.

statement.

are

77

full language.

as in Section 7

however,

or

data,

and

the

'PNAME'

statement

the

digits --

The

the

end

batting

average will be

one

END

statement

of

the

Statements

listed below

available in

not

nonexecutable.

control

or

value

to

To

the

simplify of ANSI

program

of

field will be a

labeled 10.

integer

program.

according

FORTRAN

the

ANSI

standard.

Executable

execution.

data

and

The

printed.

digit

and

is

an

indicator

Every

program

to

their

77 subset

comparison,

standard.

statements

Nonex-

define

program

string

name

The

three

to

main

the

All

1.2.1 Executable Statements

1.

Arithmetic, (Chapter

2.

Unconditional,

3.

Arithmetic

4. Block

5.

CONTINUE

6.

STOP

7.

DO

statement

8.

READ,

9.

REWIND,

(Chapter

10.

CALL

11.

END

statement

logical,

3);

and

IF,

ELSE

statement

and

PAUSE

WRITE,

BACKSPACE,

6);

and

RETURN

and

assigned,

logical

IF,

ELSE,

statements

(Chapter

and

(Chapter

character

and

computed

IF

statements

and

(Chapter

4);

PRINT

statements

ENDFILE,

4).

assignment

(Chapter

END

4);

(Chapter

IF

1.2.2 Nonexecutable Statements

1.

PROGRAM SUBROUTINE

2.

DIMENSION, EXTERNAL,

3.

INTEGER,

4.

DATA

5.

FORMAT

6.

Statement

(Chapter

INTRINSIC,

REAL,

statement

function

2),

(Chapter

COMMON,

LOGICAL,

(Chapter

statement

BLOCK

5)

statements;

EQUIVALENCE,

and

SAVE

CHARACTER

3);

6);

(Chapter

DATA

GO

TO

4);

statements

4);

(Chapter

OPEN,

5);

(Chapter

5).

statements;

statements

(Chapter

6); and

3),

IMPLICIT

5)

statements;

type

statements

ASSIGN

(Chapter

4);

CLOSE

FUNCTION,

(Chapter

statement

4);

statements

and

3),

3);

1-3

Introduction

To

FORTRAN

1.2.3 Order of Statements

The

following

1.

Comment after

The

2. program. as the first statement

FORMAT

3.

IMPLICIT

4.

5. All specification statements (lists 1

DATA

must

6.

The

rules for ordering

order

must

be observed in coding

lines can

the

END

PROGRAM

FUNCTION,

appear

statement.

statement can

before

SUBROUTINE,

of a subprogram

statements

can

appear

statements must precede all

statements, which

must

precede all executable statements.

last line

of a program

FORTRAN

unit must be the

statements are summarized in Figure 1-2.

FORTRAN

or

between statements. They

appear

only as the first statement

and

BLOCK

statements lines:

cannot

of

DATA

can

appear

a main

only

(Section 2.1.1).

anywhere before the

other

specification statements.

and

2 in section 1.2.2) must precede all

END

statement.

precede all statement function statements, which

END

statement.

FORTRAN-SO

PROGRAM,

Comment

FORMAT

Lines Statements

Figure 1-2.

FUNCTION,

END

Statement

Order

of

FORTRAN

SUBROUTINE,

or

Statement

IMPLICIT

Other

Statements

Specification

Statements

DA

T A Statements

Statement

Function

Statements

Executable Statements

Statements

BLOCK

DATA

1-4

CHAPTER 2

The

chapter discusses the concepts

and

elements

2.1

FORTRAN Program Structure

of a FORTRAN

and

program.

terminology used to describe the structure

2.1.1 Program U nits and Procedures

The

scope

of

many

FORTRAN

gram

unit

is

either a main program

A main program can start with a programs start with either a ment. A have any

Subroutines tions are further defined to be created outside a call library. Procedures are discussed in detail in

FORTRAN

number

and

an

external procedure written in

program

of

subprograms

functions are called procedures. Subroutines

FORTRAN

operations

or

PROGRAM

FUNCTION,

must have one

(Figure 2-1).

external procedures. External procedures can be

program also; for example, a

is

defined to be a program unit. A pro-

a subprogram.

SUBROUTINE,

and

PL/M-80

Chapter

FORTRAN

statement, though it need not. Sub-

or

BLOCK

only one main program

and

FORTRAN

and

stored in

5.

an

CONCEPTS

DATA

'external'

program can

ISIS-II system

and

state-

may

func-

MAIN

PROGRAM

[PROGRAM]

•

END

SUBPROGRAMS

SUBROUTINE

•

FEN:

FUNCTION

•

Fig.

..

END

BLOCK

~

END

f'

'-----"

MISC. EXTERNAL PRO-

CEDURES

~

2-1

Program Units

•

DATA

•

• • •

-

~

..

1-

• • •

•

J

P-'S~UB=R=OU=T=IN=E

END

J

FUNCTION

END

J

BLOCK

END

,...

DATA

2-1

FORTRAN

Concepts

2.1.2 The PROG RAM Statement

The

PROGRAM

but

when present must be the first statement

PROGRAM name

where

'name'

is

allowed per program.

FUNCTION,

statement

is

the symbolic name

SUBROUTINE,

is

The

used

to

of

main program can contain any other statement except

BLOCK

name a program. This statement

of

a main program.

the program. Only one

DATA,

SAVE,

or

It

has the

PROGRAM

RETURN.

is

optional,

format

statement

FORTRAN-SO

The scope moment, suffice it program. DATA

of

symbolic names

It

cannot

subprogram,

is

discussed later in this chapter (section 2.5.5).

to

say

that

the program name be the same as the name common

block,

or

'local' symbol name in the main program.

is

of

'global'

an

to the entire executable

external procedure, BLOCK

For

the

2.1.3 Statements and Lines

A FORTRAN-SO source program

statements.

Compiler controls direct the operation it

what

kind

of

output ed in detail in the compiler manual where relevant. In general, controls can be embedded in code

and

are identified by a

All

but

two types

by

that

keyword. the keyword do

not

example

'PROGRAM.'

begin with keywords. The

of

an arithmetic assignment statement.

to

of

FORTRAN

For

example, the

produce, the form

is

made up

operator's

'$'

in the first character position

Only 'assignment'

manual,

statement begin with a keyword

PROGRAM

'AVG = HITS/AB'

of

a particular

of

list

compiler controls

output,

and

a few will be mentioned in this

statement

and

'statement

and

FORTRAN

etc. Controls are discuss-

('column'

just

statement in Figure

compiler, telling

FORTRAN

1).

and

are identified

described begins with

function' statements

source

1-1

is

an

2.1.3.1 Statement Labels. Any statement can be labeled; any statement to be

referenced from elsewhere in the unsigned, nonzero, integer ment's

gram

initial line. No two statements may have the same label within the same pro-

unit.

constant

program

must be labeled. The label

written anywhere in columns

is a 1-5

1-5

of

digit,

a state-

2-2

2.1.3.2 Line

first line

ment are called

FORTRAN

A (referred to as statement begins in column 7. A statement can extend over nine continuation lines (columns 7-72) for a total

An

integer anywhere in columns tains a is

Specific Intel mat.

'0,'

a continuation line. Columns

See Section

Format.

of

a statement

continuation lines.

line

can

'columns'

the line

is

FORTRAN

F.2.4

A

FORTRAN

is

called the initial line; subsequent lines in the same state-

have up to 72 characters. The first six character positions

1-6) contain

of

660 characters.

an

initial line;

1-5

compilers may allow exceptions to the

of

Appendix F for details.

statement consists

information

1-5

is

a statement label.

if

column 6 contains any

of

a continuation line must be blank.

characterizing the line.

of

If

column 6

one

or

more lines. The

is

blank

other

character, the line

standard

The

line for-

actual

or

con-

FORTRAN-80

2.2 FORTRAN Statement Elements

A

FORTRAN

• Statement identifier (keyword), such as

• Function identifiers, such as SQRT(A)

• Constants, such as 3.142857

• Variables, such as A

• Operators, such as *

•

Combinations mathematical expressions, such as A

Statement variables, and

in

Chapter

2.2.1 Character Set

statement can include the following elements:

PROGRAM

or

FLOA

or

'STRING'

or

AB

or

.AND.

of

the above into value assignments, such as X =

*B

+ SQRT(C)

and

function identifiers are the subjects

operators,

3.

and

expressions are described in the remainder

T(I)

or

of

Chapters

INTEGER

3-6.

y*Z,

Constants,

of

this

FORTRAN

or

into

chapter

Concepts

The FORTRAN-80 character set consists 0-9,

and

the special characters listed below.

pr~5~ss~~1~9ItliJ~~t~~p:r~rl~iqg·

l~t~ng.sequ¢nce()fthe¢h~(actersisthat

SPECIAL

= Equal Sign

CHRACTERS

Blank

•• ~ ..

~~

of

the alphabetic characters A-Z, the digits

The

set

ofcnar&ctetsreptesentable

••

~I.gr~l?hi¢s~A9th~blan~cryar~cter

of~he

·AS~TTqhaT(\cter$et(Appendix·

'.

+ Plus

Minus * Asterisk / Slash ( Left Parenthesis ) Right Parenthesis

Comma

Period

Single

Quote

$ Dollar Sign

#Pol.1ndSign

Generally, blanks have no meaning in a improve program readability.

For

FORTRAN

example,

statement

and

should be used

in

The·.

E).

the

col*

to

A =

8*C

+ (D* *2/E)

and

A

are equivalent statements. Blanks are counted in the total characters allowed in a

however. They are also significant in character strings dard

line format. They

8*C

+ (D* *2/E)

and

are

not counted in the memory space occupied by a

FORTRAN

in column 6

statement,

of

the stan-

program.

2-3

:FORTRAN

Concepts

2.2.2 Constants and Variables

FORTRAN-SO

The value next. gram execution

The

of

a constant does not change from one execution

value

of

a variable, on the other hand,

or

between runnings

of

the program.

is

subject to change during pro-

For

of a program

example, in the statement

C=A**2+B

the

'2'

is

constant, whereas A,

an

earlier calculation

or

A constant appears as its actual value. A variable has a

B,

and

C are variable

value assignment.

and

may change as the result

symbolic name

that

1-6 alphanumeric characters. The first character must be alphabetic. Thus, all

following are valid variable names:

K

XYZ

B52

ERROR8

STEP3

Every constant Arithmetic constants

2.2.2.1 Data Types. Arithmetic constants and variables are

real (sometimes called 'fixed

and

variable has a data type

and

variables also have an associated

point'

and

'floating

and

point').

length associated with it.

number

base.

of

type integer

to the

of

can be

of

the

or

An

integer

or

'-' include a decimal point preceded by ne.ed

The internal representation, the precision,

constant

sign (0, 123, - 34, + 5). A

an

not

have a decimal point (4E3). Again, the exponent may be signed.

4.2E3

4.2E+3

4.2E-3

is

written without a decimal point

'+'

is

assumed if no sign

and

optional sign (5.,

'E'

may follow a real constant

X

103 .or 4200)

(4.2 (same as above) (4.2 x

10-3 or

.0042)

and

can be preceded by a

is

present. Real constants

.5,0.5,

the range

.0005).

and,

in this case, the real constant

of

real values

An

integer exponent

conforms

'+'

to the floating-point conventions established for the particular processor being used. See section

An

integer variable name begins with one

'N.'

are assumed using

Constants Logical

logical

F.l.

of

the alphabetic

Variables beginning with an alphabetic character

to

be type real. This implicit naming convention can be circumvented

Type

statements, however (see section 3.1).

and

data

constant

.TRUE

variables can also be

may have only the values

are:

.

of

type logical

'true'

or

'false.'

characters'!'

other

than

I,

type character.

The possible forms

J,

K,

through

L,

M,

or

of

N

. FALSE.

a

2-4

FORTRAN-80

FORTRAN Concepts

Character character the form the string

data

is

a string

is

valid

and

of

a string

is

represented by a double

of

any characters representable in the processor. The blank

significant in a character constant. A character

of

characters

surrounded

apostrophe.

by apostrophes.

An

apostrophe

A character constant can have

constant

1-255 characters.

'ARITHMETIC 'MURPHY'S

For

the sake

of also supports Hollerith type Hollerith type

2.~~~.2~~t3Lellgth.ATeal

hitS).

Atlintegtrm~~pc¢upY?l1e,>~W9,.()rfout

spe~ifiedw~eT\th,e"ariably,

Jf~ou~rnberpas~jS'specified

deciO}alaT\<lits'l~ngthist~e

base

.,is

speci~ied.

~~n~t~js~~t~rmJned

OVERFLOW

LAW'

compatibility with earlier versions

is

summarized in Appendix C.

type is

s~Ille;asthe

for,an.i~teger,,~onstant

implicitly

ERROR'

data

under the guise

v~lu~

defined

[or

an

integer constant, the ,constant

by

the

processor from the base

of

FORTRAN,

of

arithmetic/logical types. The

alwij.yso¢cupies four

bytes.F?ran

(section 3.1)

integervariahle, the length is

Or

by

jntegervaria,bIedefault length.,

(a$,des~rib:d

j~

the, next ,'.subsection).

FORTRAN-80

hytesof

default (section F

is

assumed to he

and

number

pftlJeirrteger.

within

memory

If

a

number

of

digits

has

(32

.2~6).

the

~~~.4.~~~~~e~.~~~~

th~~(#!il11ql~t),Illp:erb(l$.ei$assll~ed

can;bebinary,()etal~"

.•

,<~()r

.~ritliineti9·.·

or hexadecimal

••

(irlte~~r~r/~~~~)c()nst~~tS'.and

with.thefollQwi'Q8.e~(;eption~',

as

well.

·,luteger

',variables,

••

constants

2-5

FORTRAN

Concepts

The

or

where:

possibleJorms

[s]d"

.

[sl#d

... b

s

is

an

of

aninteger

optional

constant are:

+ or

-.

FORTRAN-SO

sign

d

is

a digitor.one

of

the letters

b designates the number base

lfthe

numher base specjfier

can

contain

specifier

is interpreted can·contain spe¢ifiedas

only

'8'

is

present,

asa

only the digits· 0-7 and is

the

digitsO~9artdjsinterpretedas

binary number.

base, the number

the

character

is

absent or is the letter

leo'

can

interpreted as a hexadecimal number. The

following

are valid

integer

constants:

o

23

+64101

-#14010

#100010108

-#100010108

-#4567Q +#AF2CH

2.2.3 Arrays

Frequently, still be is called

able

an

the

programmer

to

refer

array.

will

individually

want

to

elements

A~F

and

is

one

of

>'D/thecharacler

a

decimal

stringm

ust contain only the digits o and 1

or

'Q'

is specified as

interpreted

as

an

contain the digits 0-9

to

refer

to a group

in

the

group

the letters

number

thebase,

octal number

or

the

of

data

as

necessary.

D,B,O;

string

..

If

Q,

the

or

'd

... '

base

H

and

the

numper

..

If

'H'

is

lettersA~Fand

by

one

name

Such a group

is

and

2-6

An

array name is

DIMENSION

array element is

ray

name

qualified

The

following generate and PNAME(3),

four

batting

averages. AB(3),

PNAME

GEHRIG OTT

RUTH

We

can

refer

to

hits

for

'OTT'

AVG(3).

the

symbolic

statement,

one

table

1

~dimensional

member

by

a subscript

could

Thus

HITS(3),

type

be

arrays.

the

statement,

in

produced

and

AB

49

60

54

any

can

element

be

in

referenced

name

the

group

enclosed

The

array

A VG(3).

HITS

14

21

18

these

arrays

as

HITS(2)

assigned

or

COMMON

of

data.

in

parentheses.

by

rewriting

table

lists

definitions

AVG

.286 .350 .333

by

using a

and

the

array

when

statement

An

array element name is

the

program

three

players,

for

these

four

subscript.

the

batting

average

it

is

defined

(Chapter

in

Figure

times

arrays

For

example,

for

at

bat, could

RUTH

3). an

1 ~ 1

in a

An

ar~

to

hits,

be

the

as

FORTRAN-80

2.2.4 Expressions and Operators

An

expression

parentheses appear cessing statements (e.g., IF (CALLSUB(X+l,

in assignment statements (e.g., A = B + C) as controls in certain

is

a combination

and

may also include functions (discussed in

Y).

of

numbers, symbols,

FLAG

.NE.

3

GO

TO

and

250),

operators.

Chapter

and

It

5). Expressions

in subroutine calls

may

data

FORTRAN

include

pro-

Concepts

FORTRAN

2.2.4.1 Character Expressions. A

character

reference. The expression

2.2.4.2 Arithmetic Expressions.

computation.

values representable in the processor (see section

tion produces values outside this range, the results are undefined.

Arithmetic operands must identify values

2.2.4.2.1 Arithmetic

has four kinds

constant,

This

computation

Operator

**

/

*

+

of

character

a character variable reference,

may

be enclosed in parentheses.

An

arithmetic expression performs a numeric

is

limited by the range

of

Operators.

Meaning

Exponentiation Division Multiplication U

nary

Unary

The

arithmetic

or

binary addition

or

binary subtraction

expression consists

F.l).

type integer

operators

or

a character

and

If

any

or

real.

are:

precision

part

of

either a

array

of

numeric

of

the computa-

element

The following expressions calculate the perimeter, square with side

SPERIM = SQAREA = SQDIAG = SQRT (2*(S* *2))

length'S.'

4*S

S**2

area,

and

diagonal length

of

a

2-7

FORTRAN Concepts

FORTRAN-80

Fig.

2w$

·.type,. Length,

andJnterpretatbin

As these figures indicate, mixed-mode arithmetic operands This conversion

In the case

If

the magnitude

the

to the same type (the type

is

unnecessary when a real

of

an

integer divided by

The

value

of

1/3

is

The

value

of

8/3

is

The

value

of

-8/3

of

an

number

of

bytes shown

of

another

0

2

is

-2

arithmetic result

in

these figures, the result

the result) before performing the

number

is

integer, the remainder

is

too

large for the processor

2.2.4.3 Relational Expressions

Relational expressions return a

TRUE

or

2.2.4.3.1 Relational

compare

FALSE

Operators.

two arithmetic

result

of

The relational

or

type logical.

operators

o~(O~1**QP2)

is

done

by converting

raised to

an

integer power.

is

truncated.

to

is

undefined. See section

two

character

expressions

are:

both

operation.

represent in

F.I.

and

2-8

Operator

.LT. .LE.

.EQ.

.NE. .GT. .GE.

Meaning

Less

than

Less

than

Equal

Not

equal Greater Greater

or

than than

equal

or

equal

FORTRAN-SO

f'ORTRAN

Concepts

Relational expressions

IF (NUMB .GT.

IF

(PNAME .EO. 'GEHRIG') PRINT 20, PNAME, AVG

2.2.4.3.2 tional tion

If

the

expressions.

is evaluated as

where operator

2.2.4.3.3 tional expression tion

If

two length character precedes dix E).

Interpretation

expression

set

up

by

the

operands

EXP1

(EXP1

'0'

set

up

character

of

are

The

operator

if

- EXP2)

is the same type as

in

both

Interpretation

by the

the

longer by

expression

the

value

is

TRUE

operator,

of

relational expression

it were written

operator

expressions.

is

TRUE

operator,

operands

of

are

commonly

99)

STOP

of

if

and

different

EXP2

of

if

and

adding

EXP 1 is

EXP2

used in

Arithmetic

the values

is

FALSE

types, type conversion

the

Relational Expressions.

of

the

otherwise.

0

(EXPI -EXP2)

Character

the values

is

have

different

considered

in

the

Relational Expressions. A

of

the

FALSE

blanks

ASCII

otherwise.

lengths, the

on

the right

to

be less

collating sequence,

IF

statement

operands

and

'operator'

operands

than

(Chapter

satisfy the relational condi-

is

similar

satisfy the relational condi-

shorter

of

EXP2

to

is the same relational

is

the

character

if

and

4).

An

arithmetic

that

of

arithmetic

character

'extended'

the value

vice versa (Appen-

string.

of

to

EXP

rela-

the

The

1

2.2.4.4 Logical Expressions. A logical expression

tion

and

returns a TRUE single logical ment

reference, logical

tion

of

2.2.4.4.1

2.2.4.4.2 involving

The

logical expression has

logical

Logical

Operator

.NOT. .AND.

.OR.

.EQV.

.NEQV.

Value

.NOT.

operand

operands

Operators.

and

is

or

FALSE

(logical

function joined

Meaning

Logical Logical Logical inclusive Logical equivalence Logical nonequivalence

Length

as follows:

of

OP1

TRUE

result

constant,

reference,

by logical

The

logical

negation

conjunction

Logical Expressions.

.NOT.OP1

FALSE

FALSE TRUE

the

opposite

of

type logical. This expression can be a

logical variable reference, logical

or

relational expression)

operators

disjunction

value as its

and

are:

operand.

performs

parentheses.

The

value

a logical

or a combina-

of

a logical

computa-

array

ele-

operand

2-9

FORTRAN Concepts

The true. Otherwise, execution stops.

10

following example passes

FLAG = FLAG

+ 1

control

to

line

10

if

the logical variable

DONE

is

not

FORTRAN-SO

DONE = (FLAG IF

(.NOT.

GOTO

DONE)

10

.GT.

99)

THEN

ELSE

STOP

ENDIF

The

value when two logical

OP1

TRUE TRUE

TRUE

FALSE FALSE

If

both

operands

This example achieves the same effect as the last example.

IF

(FLAG

are

.GT. 0 .AND.

operands

OP2

are

combined

OP1

TRUE

FALSE

TRUE

FALSE

true, the logical expression

FLAG

.LE.

FALSE FALSE FALSE

99)

GO

by

.AND.

.AND. OP2

is

true.

TO

10

STOP

The

value when two logical

operands

are

combined

by . OR.

is

as follows:

is

as follows:

2-10

If

either

operand

The

following

IF

The

value when two logical

If

both

statement

(FLAG

operands

.EO.

OP1

TRUE TRUE

FALSE FALSE

is

true,

50

OP1

OP2

TRUE

FALSE

TRUE

FALSE

the logical expression

branches

.OR.

on

FLAG

operands

OP2

either

.LE.

are

10)

combined

OP1.0R.OP2

TRUE TRUE TRUE

FALSE

is

true.

of

two conditions.

GO

TO

OP1

.EQV. OP2

TRUE TRUE TRUE TRUE

FALSE FALSE

are

logically the same, the logical expression

FALSE TRUE FALSE

FALSE FALSE

TRUE

250

by .EQV.

is

as follows:

is

true.

FORTRAN-80

FORTRAN Concepts

The following statement returns whenever the two logical operands are logically equivalent.

IF

(FLAG1

The

value when two logical

.EQV.

FLAG2)

operands

RETURN

are combined by

.NEQV.

is

as follows:

OP1

TRUE TRUE

FALSE FALSE

If

both

operands are logically different, the logical expression

The

following statement continues execution

IF

(FLAG1

.NEQV.

OP2

TRUE

FALSE

TRUE

FALSE FALSE

FLAG2)

OP1

FALSE

TRUE

if

the two operands are

CONTINUE

.NEQV. OP2

is

true.

not

equivalent.

2.2.4.6

Expressions are generally evaluated left are evaluated before When

Precedence

two operators have equal precedence, the leftmost

of

Operators.

other

operators

to

that

right.

Operators

immediately precede

with higher precedence

is

evaluated first.

or

follow them.

2-11

.FORTRAN

Concepts

FORTRAN-SO

Parentheses can be used to override pression enclosed in parentheses nermost are evaluated first.

15/3 + 18/9 = 5 + 2 = 7 15/(3 + 18/9) = 15/(3 + 2) = 15/5 = 3

The

following lists the precedence

• Parenthesized expressions

• Exponentiation: **

• Multiplication/Division: *, /

•

Addition/Subtraction:

• Relational

•

Logical/Boolean

•

Logical/Boolean

• Logical/

•

Logical/Boolean

Thus,

the expression

Operators:

Boolean.

.NOT. .AND.

0 R.

.EQV.,

is

of

+, - (unary

.LT.,.LE.,.EQ.,.NE.,

.NEQV.

o .OR. A + 8 .GE. C

is

interpreted as

though

it

were written

normal

evaluated first.

operators

rules

in descending order:

and

binary)

of

precedence. The

If

parentheses are nested, the in-

.GT.,.GE.

part

of

an

ex-

o .OR. ((A +

One

exception to the left-to-right rule

occur together.

A**8**C

In this case, the exponentiation

A *

*(8

* *C)

8)

.GE. C)

is

the case where two

is

interpreted right-to-Ieft as

2.2.5 Scope of Symbols

A symbolic must be alphabetic. Symbolic names may be the entire local symbol units

The following symbolic names are global to in a local context.

• Main

•

Subroutine

• External function names

• BLOCK

name

consists

program)

name

can, therefore, represent different entities in different

or

in different statement functions.

program

name

names

DATA

of

one

or

they may be local to a

subprogram

names

to

six alphanumeric characters, the first

global

(that

program

the entire

or

more

exponentiations

though

is, they may have a scope

unit

or

program

it were written

of

statement function. A

program

and

cannot

be used

which

of

2-12

The

following symbolic names are local to the

•

Array

names

• Variable names

program

unit in which they appear:

FORTRAN-80

•

Statement

function names

• Intrinsic function names

•

Dummy

Variables that

statement

procedure

appearing

only.

names

as

dummy

arguments

FORTRAN

in a statement function have a scope

Concepts

of

Common block intrinsic function in a function as a function. pearance

block names

name

in a

program

are

generally global,

unit

may

also be the

subprogram.

common

block

If a name

name, is

used for

however,

both a common

identifies only the local entity except in

if

the

2.3 Notational Conventions

This

manual

statements

• Special characters from the uppercase words (keywords) noted.

• Lowercase letters items must be substituted in actual statements.

• Brackets [ ]

• Ellipses (

.times in succession.

• Blanks are used to improve readability,

an

example

As

CALL

uses the following

and

concepts:

and

are

used to indicate

...

) indicate

of

the

notation

sub

[ ([arg[,arg]

notational

FORTRAN

are

to

be

words indicate nonspecific arguments for which specific

optional

that

the preceding

used, the description

...

] ) ]

but

do

admit

exceptions. A

name

of

any local entity

An

intrinsic function

program

unit does not reference

block

and

COMMON

name

a local entity, its ap-

and

SAVE statements.

conventions to describe

character

set, uppercase letters,

common

other

than

an

may

be used

that

FORTRAN-80

and

written as shown, except where otherwise

items.

optional

but

items can

appear

have no significance.

one

or

more

means the following forms

CALL

sub

CALL

sub

( )

CALL

sub

(arg)

CALL

sub

(arg, arg)

CALL

sub

(arg, arg, arg)

etc.

When

for

the actual

'sub'

and

CALL

each

statement

'arg.'

ROUT1(A, 3.72, 4.12)

of

the

CALL

statement

is

written, specific entities would be substituted

are

permissible:

2-13

CHAPTER 3

DEFINING VARIABLES,

ARRAYS,

This chapter describes the statements used to specify the types with symbolic names, how to assign values memory, are:

• Type statements:

•

• Assignment statements: arithmetic, logical,

•

3.1

The type statements REAL, confirm names beginning with the letters I-N refer

tion itself can be confirmed Type statements can also specify

and

how

to

assign values

REAL,

Array

definition statement:

ASSIGN, Memory

DATA

definition statements:

Type Statements

or

override the type implied by a symbolic name (i.e., the convention

to

a block

INTEGER,

DIMENSION

COMMON , EQUIVALENCE,

INTEGER,

or

changed by the

data

length

to

these symbols, .how to structure

of

memory. The statements described

LOGICAL,

to

integers-Section

IMPLICIT

pr

array dimension

CHARACTER,

and

CHARACTER

statement.

AND

and

lengths associated

character assignment,

BLOCK

2.2.2.1). The conven-

information.

MEMORY

IMPLICIT

DATA

are used to

that

Specifying the symbolic

function in a type statement establishes the type the program unit. The type in a

program

statement.

unit.

name

Program

of

a variable, array, external function,

of a name

names

cannot

and

be specified explicitly

subroutine names

3.1.1 REAL Type Statement

The

REAL

type statement has the format:

name

REAL

where

'name'

tion,

or

dummy

Examples:

[,name]

is

the symbolic name

procedure.

REAL TEMP REAL NUMB1, NUMB2, NUMB3

C REAL OVERRIDES

...

of

a real variable, array, array declarator, func-

IMPLICITTYPING

3.1.2 INTEGER Type Statement

of

that

name

for all appearances in

cannot

OF

NUMB=INTEGER

or

more

appear

statement

than once

in a type

The

INTEGER

INTEG

type statement has the format:

ER.fm!@ti£;l)

name

[,name]

...

3-1

Defining Variables, Arrays, And Memory

FORTRAN-80

where 'name'

is

one

of

the forms

v[*/en} ary[(d)][* len]

and

v

ary

ary(

d)

lenj.i~~~~l~9:!~~i*~~f¢~;0;(<trl·.ii)t~g~rV(l~i&l?1~·9t

is

an integer variable, function, or dummy procedure name

is

an array name

is

an array declarator

.·~rp~y¢l~w~#t,

••••.

~t$

• va,luernustuei{A, Qp4. .

•.•.•......•....•...............

:

.•••••....••..••.•.•...•....••....

..•.•..•..•.••

.•......•••....•...•...•..•••••.....••

..•.•

..

•...•

..•

..•.•

••.•.....•..•..

.

••...•.••....•...•..••.....•..•••.••......••..••.•.•.....••....•.•..••.•....••...•...•.

:

...•..•........•..•

'.. . •..••.•.•...

:

•..•...........•..•..•......•..•.•

~

.•. ~ .. : ...•..•.

~.;.::

:

•...•........

:

.•..•...•....•.•...•....•

~

... ! ..•..•.•.•.

::

....•.•• : ...••.••..

:

..•...

:.~

.••...

:::

.... : •...•.

:~

•......•.••.••.

;:.~

•...

:"

..

" . :

.•.

:...............

..••.

......

...•.•.•..•......•.....•..........•........•.

.

.....••.•.•.•..............•.••.......

::

••..•.•......•..........•

:

...•........•...•.....................•.•.•

:. " •.......•.

::......

.'

.. ' ..••.........

:..............

.•.•.

.•...•.....•.•••.••.••..••....•..•..........

....•..•...

. .

..•............•.•.....•.........•.

.•.•...........

... . ..•..•.•

.•... . .....

:.:.

•......

.....•.•..

.......•

..•....

........ • .'. : ..• : ....................•..

:". • .......

":

"'

•....

X~~~~P~f.~·

~.~~.~

•.• · ••.

sp~cifi9~tiqp;.·i~~;:~i~t.7~¥X~11Q~.i119·

:~l'r~~i/t~~

def:~1l111efl.gthqf··(l~··.int~$~rvad~l?1~Ofar.r;:\y

Examples:

•••

~p~~~

••

ite~.·i~···

..

·~J.1estttJe~.el1ttlp~n~yil1~

.•

J~l1~tl)·~~p~j~~

f~E~.~~.~~

•.

··.·.~.~ffi~.~~~~rl~.fP~~~~~.n~··.·~e~~e~~?rf;l.·.·~·fir~~B:.~

.•

~2·itGB'li§!er

•.

·.tQ

•.

·•

~~p~~~rfty.·.~1~mel1t?J:f119.1e~~te:i~~R~fi~i~~~~9T$.~~rent

INTEGER TOTALS

•••

..

i~s

•.

8'Y11\1~~~~~~pe9ifi~~tio~.~

1711gt~f:()~it~~t·i~~rn

..

e1~rqentis.a;~SUlTIeg(s~ySeC!~Pfl.f,4~~).

··~BRl~~~i~?

•...

·.~

.. · ••

·ltl1gt~

.?111~\

••

~A~/.~~

INTEGER*1 DIGITS(10} INTEGER*4

TOTALS, SUBS*2, DIGITS(10}*1

3.1.3 LOGICAL Type Statement

The LOGICAL type statement has the format:

LOGICAL [*len[,]) name [,name]

where 'name' is

one

of

the forms

v[*/en]

a

ry[

(d)][

* len]

and

v is a logical variable, function, or dummy procedure name

ary

ary(d)

leit

".:

,"

.:

...•.

:::",

,"

.. " ..... ; ......

is

an array name

is an array declarator

~~~~~l~~~~~~ij~~~¢sgf#lg$!~#~y~~~~~~$qp~!t~y.~~~m*p.~.lt$¥~h!~

mu&tgf;lJ~,-·911::h

~.::.

'.:~

...

<.,

...

-.:.:'

:".".:

:::

:::,-.::".:,.\:.::.

:.:

..

:.::

.•.. ~ ..

:.:.:.::.:::

..

::

.....•• : ..•.•...... : ..•.......•............•...•...•.....•

'

•..........•...•.

::

.•.•........•..•......•..•.•.......

:

•.•. : .•..............•......................

...

..

:

•..•.•.....•.....................••.••.........•.

::

...•.....................•..•.•..•...•............•..•...............•....•....••......................................•....•.•............

::

............•..............•.

. . .

:

....

;:

......

::

•...•.•..•........

:

...........•..............•....

:

..••....•..

::

..

:::

..... : ..

::

•.... : ......••....•.•.••.....

:.:::.:

..•...

:.: ...

:.

..

>:.:

..

: .

"."

.....•... - '

..

3-2

~~~~<itel'tli~l

s~:vifi~~t19rr.iPlnae~j~t~ly()n9W:il1g~n

ao'a~;

.the,l~ngthi~ppHe$

default.· length . ofalOgical

.••.•

tb!~'~f~~~nt[lQ~.··

..

t().·.eacl1··a,rray.el~~ent

v~riable

•.

~~~i!!$i~s.~~P

.

i~enJ.i~t~el~ng~~fQ~~'a~r~t~tni~I1~>'.~9r~rt

Of

arrayelenlent

..

I~pj~~~~~~~~lR~~~~~;~.~~~w~~

...••

If

~.~.

·~~ll~t~issp~~~f~e~yttl~current

..

is

!l$$91l1eO,f$ee$ectiPfl.ll,2.(j).

FORTRAN-SO

Examples:

LOGICAL *2 FLAG

LOGICAL* 1 FLAGS(10)

Defining Variablest Arrayst

And

Memory

LOGICAL

*4 FLAG1, FLAG2, SWITCH(5)*1

3.1.4 CHARACTER Type

The

CHARACTER

CHARACTER [* len[,]] name [,name]

where

'name'

v[* len] ary[(d)][* len]

and

v

ary

ary(d)

len

type statement has the format:

is

one

of

the forms:

is

a variable name

is

an

array

name

is

an

array

declarator

is

the length

character

(number

array

Statement

of

element.

...

characters)

of

a character variable

or

The length specification immediately following the keyword to

each item in the statement not having its own length specification. A length specification immediately following an item array, the length applies length

of

a character (one byte)

Examples:

CHARACTER*15 CHARACTER*12 NAMES(50), CITIES(50), STATES(50)*5 CHARACTER LETTER

3.1.5 IMPLICIT

An

IMPLICIT trinsic function names) PLICIT

specification in a

statement can also be overridden by statement containing the same symbolic name.

statement defines the type and length for symbolic names (except in-

types can be overridden, however, by type statements

to

each array element.

STRING

Statement

that

begin with the letter(s) specified by

FUNCTION

is

assumed.

statement. The length specified in

an

is

the length for

If

no

INTEGER,

length

LOGICAL,

CHARACTER

that

item only.

is

specified, the

IMPLICIT.

or

by

an

or

CHARACTER

standard

explicit type

IMPLICIT

applies

For

an

IM-

3-3

Defining Variables, Arrays,

The

IMPLICIT

And

Memory

statement has the format:

FORTRAN-SO

IMPLICIT

typ

(let

[,/et] ... ) [,typ

(let

[,let].

..

)].

..

where

typ

let

is

INTEGERf*bml ,

CHARACTER[*

is

a single letter

REAL,

len]

or

LOGICALt~lejz],

a range

of

letters in alphabetical

or

order

(e.g., C, I-M, N-Z)

The

IMPLICIT

must

precede all other specification statements in that program unit. The

unit can have more specified

more

statement applies only to the program unit in which it appears

than

one

than

IMPLICIT

once.

statement,

but

the same letter

cannot

and

program

be

Example:

IMPLICIT REAL(A-B, D-H), CHARACTER IMPLICIT INTEGER (I-N), LOGICAL

(C)

(O-l)

Unless these implicit definitions are overridden, the following symbols would have the types indicated.

AVG CNAME FPNUM INUM PFLAG

(REAL) (CHARACTER) (REAL) (INTEGER) (LOGICAL)

3.2 Array Definition

An

array

is

defined by assigning a symbolic name to the array

dimensions.

CHARACTER

LOGICAL

Arrays can also be defined by the DIMENSION

In any case, a symbol can be used only once in a

array declarator

not

be defined in a statement. The name

One

statement.

elsewhere:

way to

do

this

is

with type statements:

TICTAC(3,3)

TABLE(2,3,3)

COMMON

(section 3.2.1). The symbol

DIMENSION

array

name could,

statement as well as in the

of

course,

'TICTAC'

appear

and

specifying its

statement (section 3.4.2)

program

unit as

an

array name

in the example above could

CHARACTER

as a reference

or

array element

and

by the

in

an

type

3-4

TICTAC(3,2) = 'X'