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Introduction

Introduction

Topics

• History

• Objectives

• Major new features

• Other new features

• Availability of compilers

• References

• Resource list

• Fortran 90 at MCC

• Coding convention

History

• 1957 IBM Fortran

• 1966 Fortran 66 standard

• 1978 Fortran 77 standard

• 1991 Fortran 90 standard

Objectives

• Language evolution
  • Obsolescent features

• Standardise vendor extensions
  • Portability

• Modernise the language
  • Ease-of-use improvements through new features
    such as free source form and derived types

  • Space conservation of a program with dynamic memory allocation

  • Modularisation through defining collections called modules

  • Numerical portability through selected precision

• Provide data parallel capability
  • Parallel array operations for better use of vector and parallel processors

• Compatibility with Fortran 77
  • Fortran 77 is a subset of Fortran 90

• Improve safety
  • Reduce risk of errors in standard code

• Standard conformance
  • Compiler must report non standard code and obsolescent features

Major new features

• Array processing

• Dynamic memory allocation

• Modules

• Procedures:
  • Optional/Keyword Parameters

  • Internal Procedures

  • Recursive Procedures

• Pointers

Other new features

• Source form

• Specifications/IMPLICIT NONE

• Parameterised data types (KIND)

• Derived types and operator overloading

• Control structures

• New intrinsic functions

• New I/O features

Obsolescent features

• Arithmetic IF

• REAL and DOUBLE precision DO variables and control expressions

• Shared DO termination, and DO termination on a statement other than on a CONTINUE or an END DO statement

• ASSIGN and assigned GO TO statements

• Assigned FORMAT specifiers

• Branching to END IF from outside IF block

• Alternate RETURN

• PAUSE statement

• H edit descriptor

Availability

Fortran 90 compilers

• Cray CF90 - YMP (EL98), vectorising and autotasking, but limited messages and some intrinsics not tuned

• DEC Fortran 90 - DEC OSF/1 AXP, including HPF extensions

• EPC Fortran 90 - SPARC Solaris 1X and 2X, IBM RS/6000, Intel 3/486, Motorola 88000

• IBM XLF V3 - RISC System 6000

• Lahey LF90 - for DOS, Windows

• Microway - DOS, OS/2, Unix

• NA Software F90+ - 386/486, Sparc, T800, T9000

• NAG f90 - Variety of Unix platforms, and VAX VMS. Uses C as intermediate language

• Pacific Sierra VAST-90 - Uses F77 as intermediate language

• Parasoft - Uses F77 as intermediate language

• Salford FTN90 - PC implementation of NAG f90, direct generation of object code

References

• Information Technology - Programming Languages - Fortran

• Fortran 90 Handbook
  Complete ANSI/ISO Reference

• Programmer's Guide to Fortran 90

• Fortran 90

• Fortran 90 Programming

• Fortran 90 for Scientists and Engineers

• Migrating to Fortran 90

• Fortran 90 Explained

• Programming in Fortran 90

• Programming in Fortran 90

Resource list

http://www.hpctec.mcc.ac.uk/hpctec/courses/Fortran90/resource.html

which has links to:

• Fortran 90 FAQ

• Tutorials and articles available on WWW

• NAG Fortran 90 software repository

• Fortran 90/HPF email discussion group

• Fortran newsgroup in Netnews/Usenet

• Fortran market

Fortran 90 at MCC

• Cray EL98
  
  Compile with f90

• NAG f90 on Cray CS6400
  
  Compile with f90

• Salford FTN90 on fileserver MCC.FS1
  
  Compile and run with ftn90/lgo

• IBM
  
  Compile with xlf90 (Note default code generated for ibmb, ibmc, ibmd, NOT ibma)

Coding convention

Recommended by NAG and others

• Put all Fortran 90 keywords and intrinsic function names in upper case, everything else in lower case

• Indent by 2 columns in the body of program units and INTERFACE blocks, DO-loops, IF-blocks, CASE-blocks etc.

• Always include the name of a program, a subroutine and a function on its END statement

• In USE statements, use the ONLY clause to document explicitly all entities which are actually accessed from that module

• In CALL statement and function references, always use argument keywords for optional arguments