FORTRAN 90+
Yetmen Wang
ENTER
Fortran 90/95/2000
INTRODUCTION
Introduction
FORTRAN HISTORY
FORTRAN VERSIONS
FORmula TRANslation
STRENGTHS
Developed by the IBM team led by John Backus
WEAKENESSES
The first high-level programming language
PROGRAM STRUCTURE
SIGNIFICANT FEATURES
Mainly intended for mathematical computations
NEW SOURCE FORM
Areas of Application
OO PROGRAMMING

Numerical Analysis

System Simulation

Scientific Computations

Engineering Procedures
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE
Fortran 90/95/2000
INTRODUCTION
Fortran History
FORTRAN HISTORY
FORTRAN VERSIONS
Published by IBM in 1957
STRENGTHS
MS PowerStation 4.0
WEAKENESSES
Sold to Digital with DEC, it developed into Digital Visual Fotran 5.x
PROGRAM STRUCTURE
SIGNIFICANT FEATURES
Digital was later merged with Compaq; CVF 6.x emerged
NEW SOURCE FORM
CVF development team was purchased by Intel
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE
HP merged with Compaq, introducing HP CVF 6.6a
Intel Fortran, combining CVF, developed Intel Visual Fortran 8.x
Fortran 90/95/2000
INTRODUCTION
Fortran Versions
FORTRAN HISTORY
FORTRAN VERSIONS
1962  FORTRAN IV
STRENGTHS
1966  FORTRAN 66
WEAKENESSES
1978  FORTRAN 77
PROGRAM STRUCTURE
SIGNIFICANT FEATURES
NEW SOURCE FORM
OO PROGRAMMING
1992  FORTRAN 90

Array

Semi-OOP

Resembles MATLAB
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE
1997  FORTRAN 95

HPF extension

more OOP
2003  FORTRAN 2000

Fully OOP
Fortran 90/95/2000
INTRODUCTION
Strengths
FORTRAN HISTORY
FORTRAN VERSIONS
Array language and object-oriented programming
STRENGTHS
Higher computational speed compared to C/C++ and MATLAB
WEAKENESSES
Maintains plenty of legacy codes
PROGRAM STRUCTURE
SIGNIFICANT FEATURES
Easy-to-learn compared to C/C++
NEW SOURCE FORM
The majority of individuals in the numerical computing field still use
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE
Fortran to develop program(s)
Fortran 90/95/2000
INTRODUCTION
Weaknesses
FORTRAN HISTORY
FORTRAN VERSIONS
File I/O is difficult to modify and comprehend
STRENGTHS
Low reusability and high cost of code maintenance
WEAKENESSES
Lack of numerical and graphical libraries
PROGRAM STRUCTURE
SIGNIFICANT FEATURES
Difficult to convert the codes into applications
NEW SOURCE FORM
Platform porting
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE
Interfacing to other language
Fortran 90/95/2000
INTRODUCTION
Program Structure
FORTRAN HISTORY
FORTRAN VERSIONS
STRENGTHS
WEAKENESSES
PROGRAM name
IMPLICIT NONE
PROGRAM STRUCTURE
SIGNIFICANT FEATURES
declarations
NEW SOURCE FORM
OO PROGRAMMING
ARRAY PROGRAMMING
A good
description
of Fortran
programing.
POINTER
DYNAMIC STORAGE
statements
STOP
END
Fortran 90/95/2000
INTRODUCTION
Significant Features
FORTRAN HISTORY
FORTRAN VERSIONS
New Source Form
STRENGTHS
WEAKENESSES
PROGRAM STRUCTURE
Object-Oriented Programming
Array Programming
SIGNIFICANT FEATURES
NEW SOURCE FORM
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE
Dynamic Memory Allocation
Pointer
Fortran 90/95/2000
INTRODUCTION
New Source Form
FORTRAN HISTORY
FORTRAN VERSIONS
Free Format
STRENGTHS
WEAKENESSES
PROGRAM STRUCTURE
SIGNIFICANT FEATURES
NEW SOURCE FORM
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE
IMPLICIT NONE
Statements
Fortran 90/95/2000
INTRODUCTION
New Source Form – Free Format
FORTRAN HISTORY
FORTRAN VERSIONS
names of variables may consist of up to 31 characters
STRENGTHS
132 characters per line
WEAKENESSES
up to 39 continuation lines
PROGRAM STRUCTURE
SIGNIFICANT FEATURES
blanks are significant
NEW SOURCE FORM
& as line continuation character
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE
; as statement separator for multiple statements per line
! as comment symbol
Fortran 90/95/2000
INTRODUCTION
New Source Form - IMPLICIT NONE
FORTRAN HISTORY
FORTRAN VERSIONS
The first line after any USE statements
STRENGTHS
Used to inhibit the old Fortran feature that treats, by default, all
WEAKENESSES
variable beginning with the letters I, j, k, l, m, and n as integers and
PROGRAM STRUCTURE
others as real arguments
SIGNIFICANT FEATURES
NEW SOURCE FORM
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE
IMPLICIT NONE should always be used to prevent potential confusion
in variable types
Upper and lowercase letters are equivalent
Fortran 90/95/2000
INTRODUCTION
New Source Form - Statements
FORTRAN HISTORY
FORTRAN VERSIONS
INCLUDE can be used to include source text from external files
STRENGTHS
END DO statements are used to complete DO loops
WEAKENESSES
Relational Operator Alternatives
PROGRAM STRUCTURE

.LT.  <

.LE.  <=
OO PROGRAMMING

.EQ.  ==
ARRAY PROGRAMMING

.NE.  /=
POINTER

.GE.  >

.GT.  =>
SIGNIFICANT FEATURES
NEW SOURCE FORM
DYNAMIC STORAGE
Fortran 90/95/2000
INTRODUCTION
Object-Oriented Programming
FORTRAN HISTORY
FORTRAN VERSIONS
Functionality
STRENGTHS
WEAKENESSES
PROGRAM STRUCTURE
TYPE
MODULE
SIGNIFICANT FEATURES
NEW SOURCE FORM
OO PROGRAMMING
Attributes
INTERFACE
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE
Overload
Fortran 90/95/2000
INTRODUCTION
Object-Oriented Programming - Functionality
FORTRAN HISTORY
FORTRAN VERSIONS
Data Abstraction
STRENGTHS
Data Hiding
WEAKENESSES
Encapsulation
PROGRAM STRUCTURE
SIGNIFICANT FEATURES
Inheritance
NEW SOURCE FORM
Polymorphism
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE
Reusability
Fortran 90/95/2000
INTRODUCTION
Object-Oriented Programming – TYPE
FORTRAN HISTORY
FORTRAN VERSIONS
STRENGTHS
user-defined TYPE

be used to describe an object
WEAKENESSES
PROGRAM STRUCTURE
A new type can be defined in a derived-type statement, which can later

Example I
SIGNIFICANT FEATURES
Create a type COORDS_3D with three REAL components X, Y, and Z.
NEW SOURCE FORM
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER
TYPE :: COORDS_3D
REAL :: X, Y, Z
END TYPE COORDS_3D
DYNAMIC STORAGE
Create a variable of type COORDS_3D with values 0.0, 1.0, and 5.0.
TYPE(COORDS_3D) :: Pt
Pt%X = 0.0
Pt%Y = 1.0
Pt%Z = 5.0
Fortran 90/95/2000
INTRODUCTION
Object-Oriented Programming – TYPE
FORTRAN HISTORY
FORTRAN VERSIONS
STRENGTHS
WEAKENESSES
PROGRAM STRUCTURE
user-defined TYPE

Example II
Create a type NONZERO in which nonzero matrix elements are described.
TYPE :: NONZERO
SIGNIFICANT FEATURES
NEW SOURCE FORM
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER
REAL :: VALUE
INTEGER :: ROW, COLUMN
END TYPE NONZERO
Create a sparse matrix A with 100 nonzero elements.
DYNAMIC STORAGE
TYPE(NONZERO) :: A(100)
Obtain the value of A(10).
X = A(10)%Value
Fortran 90/95/2000
INTRODUCTION
Object-Oriented Programming – MODULE
FORTRAN HISTORY
FORTRAN VERSIONS
STRENGTHS
MODULE / MODULE PROCEDURE

A collection of data, type definitions, and procedure definitions which
WEAKENESSES
can be exploited by any other program unit attaching it (via the USE
PROGRAM STRUCTURE
statement).
SIGNIFICANT FEATURES

Example
Main Program
MODULE point_module
.
NEW SOURCE FORM
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE
TYPE point
REAL :: x, y
END TYPE point
CONTAINS
FUNCTION addpoints(p, q)
TYPE (point), INTENT(IN) :: p, q
TYPE (point) :: addpoints
addpoints%x = p%x + q%x
addpoints%y = p%y + q%y
END FUNCTION addpoints
END MODULE point_module
Accesses
the module.
.
.
USE point_module
TYPE (point) :: px, py, pz
.
.
.
pz = addpoints(px,py)
Fortran 90/95/2000
INTRODUCTION
Object-Oriented Programming – ATTRIBUTES
FORTRAN HISTORY
FORTRAN VERSIONS
STRENGTHS
PUBLIC and PRIVATE attributes

the specified module
WEAKENESSES
PROGRAM STRUCTURE
PRIVATE – variables/subroutines/functions defined can only be used in

PUBLIC – variables/subroutines/functions defined can be used publicly

Example
SIGNIFICANT FEATURES
NEW SOURCE FORM
OO PROGRAMMING
MODULE bank
ARRAY PROGRAMMING
PRIVATE money
POINTER
PUBLIC SaveMoney
DYNAMIC STORAGE
integer :: money = 1000000
CONTAINS
SUBROUTINE SaveMoney(num)
integer :: num
money = money+num
return
END SUBROUTINE
END MODULE
Fortran 90/95/2000
INTRODUCTION
Object-Oriented Programming – INTERFACE
FORTRAN HISTORY
FORTRAN VERSIONS
STRENGTHS
INTERFACE

A way to specify information for an external procedure
WEAKENESSES
Name of the procedure
PROGRAM STRUCTURE
Types of passed and returned parameters
SIGNIFICANT FEATURES
Whether an argument may be changed
NEW SOURCE FORM

INTERFAXE detects incorrect calls at compile time

Example
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE
INTERFACE
REAL FUNCTION DISTANCE( A, B)
REAL, INTENT(IN) :: A, B
END FUNCTION DISTANCE
END INTERFACE
Fortran 90/95/2000
INTRODUCTION
Object-Oriented Programming – Overload
FORTRAN HISTORY
FORTRAN VERSIONS
STRENGTHS
WEAKENESSES
Overload Operators

Operators can be overloaded to clarify unambiguous definitions

Intrinsic operators can be overloaded to apply to all types in a program

Overloading is encapsulated in a module
PROGRAM STRUCTURE
SIGNIFICANT FEATURES
generic operator symbol in an INTERFACE OPERATOR statement
NEW SOURCE FORM
overload set in a generic interface
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE

Example
INTERFACE OPERATOR(-)
FUNCTION DIFF(A,B)
TYPE(POINT) :: DIFF, A, B
END FUNCTION
END INTERFACE
Fortran 90/95/2000
INTRODUCTION
Array Programming
FORTRAN HISTORY
FORTRAN VERSIONS
Whole Array
STRENGTHS
WEAKENESSES
PROGRAM STRUCTURE
SIGNIFICANT FEATURES
NEW SOURCE FORM
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE
Array Section
Intrinsic Functions
Fortran 90/95/2000
INTRODUCTION
Array Programming – Whole Array
FORTRAN HISTORY
FORTRAN VERSIONS
STRENGTHS
Assignment

All arrays must conform

The operation is applied to each element of the array

Scalars broadcast
WEAKENESSES
PROGRAM STRUCTURE
SIGNIFICANT FEATURES
NEW SOURCE FORM
Declarations
OO PROGRAMMING
REAL, DIMENSION(5, 5) :: A, B
ARRAY PROGRAMMING
OR
REAL :: A(5,5), B(5,5)
POINTER
DYNAMIC STORAGE
Fortran 90/95/2000
INTRODUCTION
Array Programming – Whole Array
FORTRAN HISTORY
FORTRAN VERSIONS
Operation
21
12
7
2
3
6
8
25
2
5
4
5
PROGRAM STRUCTURE
18
42
9
6
2
7
SIGNIFICANT FEATURES
36
77
4
7
9
11
STRENGTHS
WEAKENESSES
=
x
NEW SOURCE FORM
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER
Example
Assume A and B to be two 2D arrays of the same shape.
Multiply them and assign the result to array C.
DYNAMIC STORAGE
FORTRAN 77
FORTRAN 90+
REAL A(5, 5), B(5, 5), C(5, 5)
REAL, DIMENSION (5, 5) :: A, B, C
...
i LOOP
j LOOP
C(j, i) = A(j, i) * B(j, i)
END i LOOP
END j LOOP
...
C=A*B
Fortran 90/95/2000
INTRODUCTION
Array Programming – Array Section
FORTRAN HISTORY
FORTRAN VERSIONS
STRENGTHS
WEAKENESSES
PROGRAM STRUCTURE
Declaration
REAL, DIMENSION(10, 10) :: A
Subscript Notation

( [row lower bound] : [row upper bound] : [row stride],
SIGNIFICANT FEATURES
NEW SOURCE FORM
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE
[column lower bound] : [column upper bound] : [column stride] )
Fortran 90/95/2000
INTRODUCTION
Array Programming – Array Section
FORTRAN HISTORY
FORTRAN VERSIONS
STRENGTHS
Example
REAL :: A(10, 10)
WEAKENESSES
PROGRAM STRUCTURE
SIGNIFICANT FEATURES
A(2:6, 4:8)
A(:, 1:3)
NEW SOURCE FORM
1 2 3 4 5 6 7 8 9
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE
1
2
3
4
5
6
7
8
9
1 2 3 4 5 6 7 8 9
1
2
3
4
5
6
7
8
9
Fortran 90/95/2000
INTRODUCTION
Array Programming – Array Section
FORTRAN HISTORY
FORTRAN VERSIONS
STRENGTHS
Example
REAL :: A(10, 10)
WEAKENESSES
PROGRAM STRUCTURE
SIGNIFICANT FEATURES
A(4:10, 5)
A(1:10:2, 1:10:2)
NEW SOURCE FORM
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE
1 2 3 4 5 6 7 8 9
1
2
3
4
5
6
7
8
9
1 2 3 4 5 6 7 8 9
1
2
3
4
5
6
7
8
9
Fortran 90/95/2000
INTRODUCTION
Array Programming – Intrinsic Functions
FORTRAN HISTORY
FORTRAN VERSIONS
STRENGTHS
Functions

WEAKENESSES
array manipulations
CSHIFT and EOSHIFT for shifts along array axis
PROGRAM STRUCTURE
TRANSPOSE for the transpose of a matrix
SIGNIFICANT FEATURES
NEW SOURCE FORM

SUM , PRODUCT , MAXVAL , MINVAL , COUNT , ALL , and ANY
OO PROGRAMMING
ARRAY PROGRAMMING
reduction functions

POINTER
inquiry functions
SHAPE , SIZE, ALLOCATED, LBOUND, and UBOUND
DYNAMIC STORAGE

array constructor functions
MERGE, SPREAD, RESHAPE, PACK and UNPACK
Fortran 90/95/2000
INTRODUCTION
Array Programming – Intrinsic Functions
FORTRAN HISTORY
FORTRAN VERSIONS
STRENGTHS
Example - CSHIFT
FORTRAN 77
FORTRAN 90+
PROGRAM STRUCTURE
REAL :: A(0:99), B(0:99)
REAL :: A(100), B(100)
SIGNIFICANT FEATURES
DO i = 0, 99
B = ( CSHIFT(A, +1) + CSHIFT(A, -1) ) / 2
WEAKENESSES
NEW SOURCE FORM
OO PROGRAMMING
B(i) = ( A( mod(i+99, 100) ) +
A( mod(i+1, 100) ) ) / 2
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE
ENDDO
Fortran 90/95/2000
INTRODUCTION
Pointer
FORTRAN HISTORY
FORTRAN VERSIONS
Introduction
STRENGTHS
WEAKENESSES
PROGRAM STRUCTURE
SIGNIFICANT FEATURES
NEW SOURCE FORM
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE
Association Status
Example
Fortran 90/95/2000
INTRODUCTION
Pointer - Introduction
FORTRAN HISTORY
FORTRAN VERSIONS
A pointer has the POINTER attribute and may point to another data
STRENGTHS
object of the same type, which has the TARGET attribute or an area of
WEAKENESSES
dynamically allocated memory.
PROGRAM STRUCTURE
ADDRESS
DESCRIPTOR
SIGNIFICANT FEATURES
NEW SOURCE FORM
OO PROGRAMMING
ARRAY PROGRAMMING
TARGET
Uses
POINTER

Alternative to allocatable arrays

A tool to create and manipulate dynamic data structures
DYNAMIC STORAGE
Declarations
REAL, POINTER :: Ptr(:, :)
REAL, TARGET :: TA(:, :)
Fortran 90/95/2000
INTRODUCTION
Pointer – Association Status
FORTRAN HISTORY
FORTRAN VERSIONS
STRENGTHS
Status

WEAKENESSES
Undefined – initially specified in a type declaration statement
Pointer
?
PROGRAM STRUCTURE
SIGNIFICANT FEATURES

Associated – points to a target
Pointer
NEW SOURCE FORM
Target
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER

Null – nullified by a NULLIFY or a DEALLOCATE statement
Pointer
NULL
DYNAMIC STORAGE
NULLIFY(Ptr)
DEALLOCATE(Ptr, STAT = ierr)
Fortran 90/95/2000
INTRODUCTION
Pointer - Example
FORTRAN HISTORY
FORTRAN VERSIONS
Example
STRENGTHS
REAL, TARGET :: A
WEAKENESSES
REAL, POINTER :: P, Q
PROGRAM STRUCTURE
A = 3.14
SIGNIFICANT FEATURES
P => A
NEW SOURCE FORM
Q => P
OO PROGRAMMING
A = 2.718
ARRAY PROGRAMMING
WRITE(*,*) Q
POINTER
DYNAMIC STORAGE
Q outputs 2.718
Q => P and P => A
Therefore, Q => A, whose value has changed from 3.14 to 2.718
Fortran 90/95/2000
INTRODUCTION
Dynamic Storage
FORTRAN HISTORY
FORTRAN VERSIONS
Allocatable Array
STRENGTHS
WEAKENESSES
PROGRAM STRUCTURE
SIGNIFICANT FEATURES
NEW SOURCE FORM
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE
Pointer
Fortran 90/95/2000
INTRODUCTION
Dynamic Storage – Allocatable Array
FORTRAN HISTORY
FORTRAN VERSIONS
STRENGTHS
WEAKENESSES
Acquire and return a storage area in HEAP MEMORY for an array
with attributes

Example
PROGRAM STRUCTURE
REAL, DIMENSION(:), ALLOCATABLE :: A
SIGNIFICANT FEATURES
ALLOCATE( A(5:5) )
NEW SOURCE FORM
A(j) = q
! assignment of the array
OO PROGRAMMING
CALL sub(A)
! Use of the array in a subroutine
ARRAY PROGRAMMING

POINTER
Deallocation occurs automatically reaching RETURN or END in the
program
DYNAMIC STORAGE

To prevent memory leak, allocatable arrays should be explicitly
deallocated
DEALLOCATE (A)
Fortran 90/95/2000
INTRODUCTION
Dynamic Storage - Pointer
FORTRAN HISTORY
FORTRAN VERSIONS
STRENGTHS
WEAKENESSES
PROGRAM STRUCTURE
SIGNIFICANT FEATURES
NEW SOURCE FORM
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE
Use a pointer

Can be passed to a procedure in an unallocated state

An explicit INTERFACE is required when passing a pointer to a
procedure
Fortran 90/95/2000
INTRODUCTION
Dynamic Storage - Pointer
FORTRAN HISTORY
FORTRAN VERSIONS
STRENGTHS
Use a pointer

Example
WEAKENESSES
PROGRAM STRUCTURE
Subroutine Procedure:
SIGNIFICANT FEATURES
SUBROUTINE SUB(B)
NEW SOURCE FORM
OO PROGRAMMING
ARRAY PROGRAMMING
REAL, DIMENSION (:,:), POINTER :: B
INTEGER M, N
! Assign M and N
ALLOCATE (B(M,N))
! Allocate B as a matrix
END SUBROUTINE SUB
POINTER
DYNAMIC STORAGE
Main Program:
INTERFACE
SUBROUTINE SUB(B)
REAL, DIMENSION (:,:), POINTER :: B
END SUBROUTINE SUB
END INTERFACE
REAL, DIMENSION (:,:), POINTER :: A
CALL SUB(A)
! matrix A is called and allocated in the subroutine
Fortran 90/95/2000
INTRODUCTION
FORTRAN HISTORY
FORTRAN VERSIONS
STRENGTHS
WEAKENESSES
PROGRAM STRUCTURE
SIGNIFICANT FEATURES
NEW SOURCE FORM
OO PROGRAMMING
ARRAY PROGRAMMING
POINTER
DYNAMIC STORAGE
THANK YOU!