Fortran

The Fortran Automatic Coding System for the IBM 704 (October 15, 1956), the first Programmer's Reference Manual for Fortran
Paradigm:	multi-paradigm: procedural, imperative, structured, object-oriented
Appeared in:	1957
Designed by:	John W. Backus
Developer:	John W. Backus & IBM
Typing discipline:	strong, static
Major implementations:	GFortran, Open Watcom, XL Fortran, many others
Influenced:	ALGOL 58, PL/I

Fortran (previously FORTRAN^[1]) is a general-purpose^[2], procedural,^[3] imperative programming language that is especially suited to numeric computation and scientific computing. Originally developed by IBM in the 1950s for scientific and engineering applications, Fortran came to dominate this area of programming early on and has been in continual use in computationally intensive areas such as climate modeling[1], computational fluid dynamics (CFD), computational physics, and computational chemistry for half a century. Image File history File linksMetadata Download high-resolution version (610x780, 90 KB) Summary Cover of The Fortran Automatic Coding System for the IBM 704, 1956. ... Image File history File linksMetadata Download high-resolution version (610x780, 90 KB) Summary Cover of The Fortran Automatic Coding System for the IBM 704, 1956. ... The IBM 704, the first mass-produced computer with floating point arithmetic hardware, was introduced by IBM in April, 1956. ... A programming paradigm is a paradigmatic style of programming (compare with a methodology, which is a paradigmatic style of doing software engineering). ... A multiparadigm programming language is a programming language that supports more than one programming paradigm. ... This article or section does not cite its references or sources. ... In computer science, imperative programming, as opposed to declarative programming, is a programming paradigm that describes computation in terms of a program state and statements that change the program state. ... Structured programming can be seen as a subset or subdiscipline of procedural programming, one of the major programming paradigms. ... Object-oriented programming (OOP) is a programming paradigm that uses abstraction to create models based on the real world. ... 1957 (MCMLVII) was a common year starting on Tuesday of the Gregorian calendar. ... John Backus (born December 3, 1924) is an American computer scientist, notable as the inventor of the first high-level programming language (FORTRAN), the Backus-Naur form (BNF, the almost universally used notation to define formal language syntax), and the concept of Function-level programming. ... John Backus (born December 3, 1924) is an American computer scientist, notable as the inventor of the first high-level programming language (FORTRAN), the Backus-Naur form (BNF, the almost universally used notation to define formal language syntax), and the concept of Function-level programming. ... Big Blue redirects here. ... In computer science, a type system defines how a programming language classifies values and expressions into types, how it can manipulate those types and how they interact. ... In computing, strongly-typed, when applied to a programming language, is used to describe how the language handles datatypes. ... On computer science, a datatype (often simply type) is a name or label for a set of values and some operations which can be performed on that set of values. ... GFortran is the name of the GNU Fortran 95 compiler, which is part of the GNU Compiler Collection. ... ALGOL 58 is the first language in the ALGOL programming language family. ... PL/I (Programming Language One, pronounced pee el one) is an imperative computer programming language designed for scientific, engineering, and business applications. ... General-purpose programming language or General purpose Softwares refers to a type software that is suitable for most ordinary computer applications. ... ... In computer science, imperative programming, as opposed to declarative programming, is a programming paradigm that describes computation in terms of a program state and statements that change the program state. ... A programming language is an artificial language that can be used to control the behavior of a machine, particularly a computer. ... Numerical analysis is the study of approximate methods for the problems of continuous mathematics (as distinguished from discrete mathematics). ... Scientific computing (or computational science) is the field of study concerned with constructing mathematical models and numerical solution techniques and using computers to analyze and solve scientific and engineering problems. ... Big Blue redirects here. ... The 1950s was the decade spanning from the 1st of January, 1950 to the 31st December, 1959. ... Climate models use quantitative methods to simulate the interactions of the atmosphere, oceans, land surface, and ice. ... A computer simulation of high velocity air flow around the Space Shuttle during re-entry. ... Computational physics is the study and implementation of numerical algorithms in order to solve problems in physics for which a quantitative theory already exists. ... Computational chemistry is a branch of chemistry that uses the results of theoretical chemistry incorporated into efficient computer programs to calculate the structures and properties of molecules and solids, applying these programs to real chemical problems. ...

Fortran (an acronym derived from The IBM Mathematical Formula Translating System) encompasses a lineage of versions, each of which evolved to add extensions to the language while retaining compatibility with previous versions. Successive versions have added support for processing of character-based data (FORTRAN 77), array programming, module-based programming and object-based programming (Fortran 90/95), and object-oriented and generic programming (Fortran 2003). It has been suggested that this article or section be merged with Backronym and Apronym (Discuss) Acronyms and initialisms are abbreviations, such as NATO, laser, and ABC, written as the initial letter or letters of words, and pronounced on the basis of this abbreviated written form. ... Fortran (previously FORTRAN[1]) is a general-purpose[2], procedural,[3] imperative programming language that is especially suited to numeric computation and scientific computing. ... Array programming languages (also known as vector or multidimensional languages) generalize operations on scalars to apply transparently to vectors, matrices, and higher dimensional arrays. ... This article or section is missing references or citation of sources. ... In computer science, Object-based has two different, non compatible, senses: A) A limited version of object-oriented programming where one or more of the following restrictions applies: there is no implicit inheritance there is no polymorphism only a very reduced subset of the available values are objects (typically the... Object-oriented programming (OOP) is a programming paradigm that uses abstraction to create models based on the real world. ... Generic programming is a way of computer programming where algorithms are written in an extended grammar and are made adaptable by specifying variable parts that are then somehow instantiated later by the compiler with respect to the base grammar. ...

History

An IBM 704 mainframe (image courtesy of LLNL)

In late 1953, John W. Backus submitted a proposal to his superiors at IBM to develop a more efficient alternative to assembly language for programming their IBM 704 mainframe computer. A draft specification for The IBM Mathematical Formula Translating System was completed by mid-1954. The first manual for FORTRAN appeared in October 1956, with the first FORTRAN compiler delivered in April 1957. This was an optimizing compiler, because customers were reluctant to use a high-level programming language unless its compiler could generate code whose performance was comparable to that of hand-coded assembly language. Image File history File links Ibm704. ... Image File history File links Ibm704. ... The IBM 704, the first mass-produced computer with floating point arithmetic hardware, was introduced by IBM in April, 1956. ... This article or section does not cite its references or sources. ... Aerial view of the lab and surrounding area. ... John Backus (born December 3, 1924) is an American computer scientist, notable as the inventor of the first high-level programming language (FORTRAN), the Backus-Naur form (BNF, the almost universally used notation to define formal language syntax), and the concept of Function-level programming. ... Big Blue redirects here. ... The IBM 704, the first mass-produced computer with floating point arithmetic hardware, was introduced by IBM in April, 1956. ... A diagram of the operation of a typical multi-language, multi-target compiler. ... Compiler optimization techniques are optimization techniques that have been programmed into a compiler. ... A high-level programming language is a programming language that, in comparison to low-level programming languages, may be more abstract, easier to use, or more portable across platforms. ... An assembly language is a low-level language used in the writing of computer programs. ...

The language was widely adopted by scientists for writing numerically intensive programs, which encouraged compiler writers to produce compilers that could generate faster and more efficient code. The inclusion of a complex number data type in the language made Fortran especially suited to technical applications such as electrical engineering. In mathematics, a complex number is a number of the form where a and b are real numbers, and i is the imaginary unit, with the property i 2 = −1. ... A data type is a constraint placed upon the interpretation of data in a type system in computer programming. ...

By 1960, versions of FORTRAN were available for the IBM 709, 650, 1620, and 7090 computers. Significantly, the increasing popularity of FORTRAN spurred competing computer manufacturers to provide FORTRAN compilers for their machines, so that by 1963 over 40 FORTRAN compilers existed. For these reasons, FORTRAN is considered to be the first widely used programming language supported across a variety of computer architectures ^{[citation needed]}. The IBM 709 was an early computer system introduced by IBM in August, 1958. ... IBM 650 front panel, showing bi-quinary indicators IBM 650 front panel, rear view The IBM 650 was one of IBM’s early computers, and the world’s first mass-produced computer. ... The IBM 1620 was announced by IBM on October 21, 1959 and marketed as an inexpensive scientific computer. It was withdrawn on November 19, 1970. ... IBM 7090 console The IBM 7090 was a second-generation transistorized version of the earlier IBM 709 vacuum tube mainframe computers and was designed for large-scale scientific and technological applications. The 7090 was the third member of the IBM 700/7000 series scientific computers. ...

The development of FORTRAN paralleled the early evolution of compiler technology; indeed many advances in the theory and design of compilers were specifically motivated by the need to generate efficient code for FORTRAN programs. A diagram of the operation of a typical multi-language, multi-target compiler. ...

FORTRAN

The initial release of FORTRAN for the IBM 704 contained 32 statements, including:

• DIMENSION and EQUIVALENCE statements
• Assignment statements
• Three-way arithmetic IF statement. ^[4]
• IF statements for checking exceptions (ACCUMULATOR OVERFLOW, QUOTIENT OVERFLOW, and DIVIDE CHECK); and IF statements for manipulating sense switches and sense lights
• GOTO, computed GOTO, ASSIGN, and assigned GOTO
• DO loops
• Formatted I/O: FORMAT, READ, READ INPUT TAPE, WRITE, WRITE OUTPUT TAPE, PRINT, and PUNCH
• Unformatted I/O: READ TAPE, READ DRUM, WRITE TAPE, and WRITE DRUM
• Other I/O: END FILE, REWIND, and BACKSPACE
• PAUSE, STOP, and CONTINUE
• FREQUENCY statement (for providing optimization hints to the compiler) ^[5]

A front panel was used on early electronic computers to display and allow the alteration of the state of the machines internal registers and memory. ... It has been suggested that Loop optimization be merged into this article or section. ...

FORTRAN II

IBM's FORTRAN II appeared in 1958. The main enhancement was to support procedural programming by allowing user-written subroutines and functions. Six new statements were introduced: This article or section does not cite its references or sources. ...

• SUBROUTINE, FUNCTION, and END
• CALL and RETURN
• COMMON

Over the next few years, FORTRAN II would also add support for the DOUBLE PRECISION and COMPLEX data types.

FORTRAN III

IBM also developed a FORTRAN III in 1958 that allowed for inline assembler code among other features; however, this version was never released as a product. Like the 704 FORTRAN and FORTRAN II, FORTRAN III included machine-dependent features that made code written in it unportable from machine to machine. Early versions of FORTRAN provided by other vendors suffered from the same disadvantage.

A pad of Fortran coding forms

Image File history File links Download high resolution version (1796x1279, 726 KB) Summary Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Fortran Punch card ... Image File history File links Download high resolution version (1796x1279, 726 KB) Summary Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Fortran Punch card ...

FORTRAN IV

Starting in 1961, as a result of customer demands, IBM began development of a FORTRAN IV that removed the machine-dependent features of FORTRAN II (such as READ INPUT TAPE), while adding new features such as a LOGICAL data type, logical Boolean expressions and the logical IF statement as an alternative to the arithmetic IF statement. FORTRAN IV was eventually released in 1962, first for the IBM 7030 ("Stretch") computer, followed by versions for the IBM 7090 and 7094. 1961 (MCMLXI) was a common year starting on Sunday (the link is to a full 1961 calendar). ... A Boolean expression is an expression that results in a Boolean value, that is, TRUE or FALSE. For example, the value for 5 > 3 is TRUE, the value for An apple is not a fruit is FALSE. Boolean expressions are used also in document retrieval. ... The IBM 7030, also known as Stretch, was IBMs first attempt at building a supercomputer. ... IBM 7090 console The IBM 7090 was a second-generation transistorized version of the earlier IBM 709 vacuum tube mainframe computers and was designed for large-scale scientific and technological applications. The 7090 was the third member of the IBM 700/7000 series scientific computers. ...

FORTRAN 66

Perhaps the most significant development in the early history of FORTRAN was the decision by the American Standards Association (now ANSI) to form a committee to develop an "American Standard Fortran." The resulting two standards, approved in March 1966, defined two languages, FORTRAN (based on FORTRAN IV, which had served as a de facto standard), and Basic FORTRAN (based on FORTRAN II, but stripped of its machine-dependent features). The FORTRAN defined by the first standard became known as FORTRAN 66 (although many continued to refer to it as FORTRAN IV, the language upon which the standard was largely based). FORTRAN 66 effectively became the first "industry-standard" version of FORTRAN. FORTRAN 66 included: The American National Standards Institute or ANSI (pronounced an-see) is a nonprofit organization that oversees the development of standards for products, services, processes and systems in the United States. ...

• Main program, SUBROUTINE, FUNCTION, and BLOCK DATA program units
• INTEGER, REAL, DOUBLE PRECISION, COMPLEX, and LOGICAL data types
• COMMON, DIMENSION, and EQUIVALENCE statements
• DATA statement for specifying initial values
• Intrinsic and EXTERNAL (e.g., library) functions
• Assignment statement
• GOTO, assigned GOTO, and computed GOTO statements
• Logical IF and arithmetic (three-way) IF statements
• DO loops
• READ, WRITE, BACKSPACE, REWIND, and ENDFILE statements for sequential I/O
• FORMAT statement
• CALL, RETURN, PAUSE, and STOP statements
• Hollerith constants in DATA and FORMAT statements, and as actual arguments to procedures
• Identifiers of up to six characters in length
• Comment lines

Hollerith constants were used in early FORTRAN programs to allow manipulation of character data. ...

FORTRAN 77

After the release of the FORTRAN 66 standard, compiler vendors introduced a number of extensions to "Standard Fortran", prompting ANSI in 1969 to begin work on revising the 1966 standard. Final drafts of this revised standard circulated in 1977, leading to formal approval of the new FORTRAN standard in April 1978. The new standard, known as FORTRAN 77, added a number of significant features to address many of the shortcomings of FORTRAN 66:

• CHARACTER data type, with vastly expanded facilities for character input and output and processing of character-based data
• IMPLICIT statement
• Block IF statement, with optional ELSE and ELSE IF clauses, to provide improved language support for structured programming
• OPEN, CLOSE, and INQUIRE statements for improved I/O capability
• Direct-access file I/O
• PARAMETER statement for specifying constants
• SAVE statement for persistent local variables
• Generic names for intrinsic functions

An important practical extension to FORTRAN 77 was the release of MIL-STD-1753 in 1978. This specification, developed by the U. S. Department of Defense, standardized a number of features implemented by most FORTRAN 77 compilers but not included in the ANSI FORTRAN 77 standard. These features would eventually be incorporated into the Fortran 90 standard. Structured programming can be seen as a subset or subdiscipline of procedural programming, one of the major programming paradigms. ... The United States Department of Defense, abbreviated DoD or DOD and sometimes called the Defense Department, is a civilian Cabinet organization of the United States government. ...

• DO WHILE and END DO statements
• INCLUDE statement
• IMPLICIT NONE variant of the IMPLICIT statement
• Bit manipulation intrinsics, compatible with similar functions included in ANSI/ISA S61.1 (1976)

The IEEE 1003.9 POSIX Standard, released in 1991, provided a simple means for Fortran-77 programmers to issue POSIX system calls. Over 100 calls were defined in the document - allowing access to POSIX-compatible process control, signal handling, file system control, device control, procedure pointing, and stream I/O in a portable manner. Industrial Real-Time Fortran (IRTF) was developed in the 1970s to augment the Fortran languge with library bindings useful for process and device control, and I/O. Also included in IRTF was a set of bit-manipulation functions which were eventually incorporated into MIL_STD-1753 for Fortran-77, and later... The Institute of Electrical and Electronics Engineers or IEEE (pronounced as eye-triple-ee) is an international non-profit, professional organization incorporated in the State of New York, United States. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...

The development of a revised standard to succeed FORTRAN 77 would be repeatedly delayed as the standardization process struggled to keep up with rapid changes in computing and programming practice. In the meantime, as the "Standard FORTRAN" for nearly fifteen years, FORTRAN 77 would become the historically most important dialect.

Fortran 90

The much delayed successor to FORTRAN 77, informally known as Fortran 90, was finally released as an ANSI Standard in 1992. This major revision added many new features to reflect the significant changes in programming practice that had evolved since the 1978 standard:

• Free-form source input, also with lowercase Fortran keywords
• Modules, to group related procedures and data together, and make them available to other program units, including the capability to limit the accessibility to only specific parts of the module.
• RECURSIVE procedures
• A vastly improved argument-passing mechanism, allowing interfaces to be checked at compile time
• User-written interfaces for generic procedures
• Operator overloading
• Derived/abstract data types
• New data type declaration syntax, to specify the data type and other attributes of variables
• Ability to operate on arrays (or array sections) as a whole in expressions and assignment statements, thus greatly simplifying math and engineering computations. These features include whole, partial and masked array assignments (such as the WHERE statement for selective assignment), array-valued constants and expressions, user-defined array-valued functions and array constructors.
• Dynamic memory allocation by means of the ALLOCATABLE attribute and the ALLOCATE and DEALLOCATE statements
• POINTER attribute, pointer assignment, and NULLIFY statement to facilitate the creation and manipulation of dynamic data structures
• CASE construct for multi-way selection
• EXIT and CYCLE statements for "breaking out" of normal DO loop iterations in an orderly way
• Identifiers up to 31 characters in length
• Inline comments
• Portable specification of numerical precision under the user's control
• New and enhanced intrinsic procedures.

In computer programming, a free-form language is a programming language in which the positioning of characters on the page in program text is not significant. ... This article or section is missing references or citation of sources. ... In computer science, a subroutine (function, procedure, or subprogram) is a sequence of code which performs a specific task, as part of a larger program, and is grouped as one, or more, statement blocks; such code is sometimes collected into software libraries. ... A Sierpinski triangle —a confined recursion of triangles to form a geometric lattice. ... A type signature defines the inputs and outputs for a function or method. ... In computer programming, operator overloading (less commonly known as operator ad-hoc polymorphism) is a specific case of polymorphism in which some or all of operators like +, = or == have different implementations depending on the types of their arguments. ... In computing, an abstract data type (ADT) is a specification of a set of data and the set of operations that can be performed on the data. ... In computer science, dynamic memory allocation is the allocation of memory storage for use in a computer program during the runtime of that program. ... It has been suggested that Software pointer be merged into this article or section. ... A binary tree, a simple type of branching linked data structure. ...

Fortran 95

Fortran 95 was a minor revision, mostly to resolve some outstanding issues from the Fortran 90 standard. Nevertheless, Fortran 95 also added a number of extensions, notably from the High Performance Fortran specification: High Performance Fortran (HPF) is an extension of Fortran 90 with constructs that support parallel computing. ...

• FOR ALL and nested WHERE constructs to aid vectorization
• User-defined PURE and ELEMENTAL procedures

An important supplement to Fortran 95 was the ISO technical report TR-15581: Enhanced Data Type Facilities, and informally known as the Allocatable TR. This specification defined enhanced use of ALLOCATABLE arrays, prior to the availability of fully Fortran 2003-compliant Fortran compilers. Such uses include ALLOCATABLE arrays as derived type components, in procedure dummy argument lists, and as function return values. (ALLOCATABLE arrays are preferable to POINTER-based arrays because ALLOCATABLE arrays are guaranteed by Fortran 95 to be deallocated automatically when they go out of scope, eliminating the possibility of memory leakage. In addition, aliasing is not an issue for optimization of array references, allowing compilers to generate faster code than in the case of pointers.) ISO has many meanings: Iso is the stem of the Latin transliteration of the Greek word ίσος (ísos, meaning equal). The iso- prefix in English derives from this and means equality or similarity. ... In computer science, a memory leak is a particular kind of unintentional memory consumption by a computer program where the program fails to release memory when no longer needed. ... In computing, aliasing is a term that generally means that one variable or some reference, when changed, has an indirect (usually unexpected) effect on some other data. ...

Fortran 2003

The most recent standard, Fortran 2003, is a major revision introducing many new features. A comprehensive summary of the new features of Fortran 2003 is available at the ISO Fortran Working Group (WG5) official Web site, and may be downloaded directly as a PDF file or gzipped PostScript file. The International Organization for Standardization (ISO) is an international standard-setting body composed of representatives from national standards bodies. ...

From that article, the major enhancements for this revision include

• Derived type enhancements: parameterized derived types, improved control of accessibility, improved structure constructors, and finalizers.
• Object oriented programming support: type extension and inheritance, polymorphism, dynamic type allocation, and type-bound procedures.
• Data manipulation enhancements: allocatable components, deferred type parameters, VOLATILE attribute, explicit type specification in array constructors and allocate statements, pointer enhancements, extended initialization expressions, and enhanced intrinsic procedures.
• Input/output enhancements: asynchronous transfer, stream access, user specified transfer operations for derived types, user specified control of rounding during format conversions, named constants for preconnected units, the FLUSH statement, regularization of keywords, and access to error messages.
• Procedure pointers.
• Support for IEEE floating-point arithmetic and floating point exception handling.
• Interoperability with the C programming language.
• Support for international usage: access to ISO 10646 4-byte characters and choice of decimal or comma in numeric formatted input/output.
• Enhanced integration with the host operating system: access to command line arguments, environment variables, and processor error messages.

Object-oriented programming (OOP) is a computer programming paradigm in which a software system is modeled as a set of objects that interact with each other. ... In object-oriented programming, inheritance is a way to form new classes (instances of which are called objects) using classes that have already been defined. ... In computer science, polymorphism means allowing a single definition to be used with different types of data (specifically, different classes of objects). ... In computer programming, a variable or object declared with the volatile keyword may be modified externally from the declaring object. ... Asynchrony is the state of not being synchronized. ... A function pointer is a type of pointer in the C and C++ programming languages. ... The IEEE Standard for Binary Floating-Point Arithmetic (IEEE 754) is the most widely-used standard for floating-point computation, and is followed by many CPU and FPU implementations. ... A floating-point number is a digital representation for a number in a certain subset of the rational numbers, and is often used to approximate an arbitrary real number on a computer. ... Exception handling is a programming language construct or computer hardware mechanism designed to handle the occurrence of some condition that changes the normal flow of execution. ... C is a general-purpose, procedural, imperative computer programming language developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system. ... The Universal Character Set is a character encoding that is defined by the international standard ISO/IEC 10646. ... A command line interface or CLI is a method of interacting with a computer by giving it lines of textual commands (that is, a sequence of characters) either from keyboard input or from a script. ... Environment variables are a set of dynamic values that can affect the way running processes will behave on a computer. ...

Fortran 2008

Efforts are underway to develop a revision to Fortran 2003, tentatively called Fortran 2008. As with Fortran 95, this is intended to be a minor upgrade, incorporating clarifications and corrections to Fortran 2003, as well as introducing a select few new capabilities. Proposed new capabilities include

• Co-array Fortran – a parallel processing model
• BIT data type

A full list is in the report "The language features that have been chosen for Fortran 2008" PDF file. Co-array Fortran, formerly known as F--, is an extension of Fortran 95 for parallel processing created by Robert Numrich and John Reid. ... A bit (binary digit) refers to a digit in the binary numeral system, which consists of base 2 digits (ie. ...

The legacy of FORTRAN

Since Fortran has been around for nearly fifty years, there is a vast body of Fortran in daily use throughout the scientific and engineering communities. It is the primary language for some of the most intensive supercomputing tasks, such as weather/climate modeling, computational fluid dynamics, computational chemistry, quantum chromodynamics, simulations of long-term solar system dynamics, high-fidelity evolution artificial satellite orbits, and simulation of automobile crash dynamics. Indeed, one finds that even today, half a century later, floating-point benchmarks to gauge the performance of new computer processors are still written in Fortran (e.g., CFP2000, the floating-point component of the SPEC CPU2000 benchmarks), an eloquent tribute to the longstanding floating-point high performance of the language. Climate models use quantitative methods to simulate the interactions of the atmosphere, oceans, land surface, and ice. ... A computer simulation of high velocity air flow around the Space Shuttle during re-entry. ... Computational chemistry is a branch of chemistry that uses the results of theoretical chemistry incorporated into efficient computer programs to calculate the structures and properties of molecules and solids, applying these programs to real chemical problems. ... Quantum chromodynamics (QCD) is the theory of the strong interaction, a fundamental force describing the interactions of the quarks and gluons found in nucleons (such as the proton and neutron). ... The Standards Performance Evaluation Corporation (SPEC) is a non-profit organization that aims to produce fair, impartial and meaningful benchmarks for computers. ...

Language features

The Fortran language features described are intended to be a fairly comprehensive overview of the Fortran language; full details may be found in any of several Fortran textbooks. Only those features widely used in new programs are described, as few of the historic features are used in modern programs. Still, most have been retained in the language to maintain backward compatibility. This article or section does not cite its references or sources. ...

This is a a comprehensive overview of features of the Fortran 95 language, the version supported by almost all existing Fortran compilers. ...

Portability

Portability was a problem in the early days because there was no agreed standard—not even IBM's reference manual—and computer companies vied to differentiate their offerings from others by providing incompatible features. Standards have improved portability. The 1966 standard provided a reference syntax and semantics, but vendors continued to provide incompatible extensions. Although careful programmers were coming to realize that use of incompatible extensions caused expensive portability problems, and were therefore using programs such as The PFORT Verifier, it was not until after the 1977 standard, when the National Bureau of Standards (now NIST) published FIPS PUB 69, that processors purchased by the U.S. Government were required to diagnose extensions of the standard. Rather than offer two processors, essentially every compiler eventually had at least an option to diagnose extensions.

Incompatible extensions were not the only portability problem. For numerical calculations, it is important to take account of the characteristics of the arithmetic. This was addressed by Fox et. al. in the context of the 1966 standard by the PORT library. The ideas therein became widely used, and were eventually incorporated into the 1990 standard by way of intrinsic inquiry functions. The widespread (now almost universal) adoption of the IEEE 754 standard for binary floating-point arithmetic has essentially removed this problem.

Access to the computing environment (e.g. the program's command line, environment variables, textual explanation of error conditions) remained a problem until it was addressed by the 2003 standard.

Large collections of "library" software that could be described as being loosely-related to engineering and scientific calculations, such as graphics libraries, have been written in C, and therefore access to them presented a portability problem. This has been addressed by incorporation of C interoperability into the 2003 standard.

It is now possible (and relatively easy) to write an entirely portable program in Fortran, even without recourse to a preprocessor.

Variants of Fortran

Specific variants

Vendors of high-performance scientific computers (e.g., Burroughs, CDC, Cray, Honeywell, IBM, Texas Instruments, and UNIVAC) added extensions to Fortran to take advantage of special hardware features such as instruction cache, CPU pipelines, and vector arrays. For example, one of IBM's FORTRAN compilers (H Extended IUP) had a level of optimization which reordered the machine language instructions to keep multiple internal arithmetic units busy simultaneously. Another example is CFD, a special variant of Fortran designed specifically for the ILLIAC IV supercomputer, running at NASA's Ames Research Center. William Seward Burroughs (1857-1898), US inventor William S. Burroughs (1914-1997), author and grandson of William Seward Burroughs Edgar Rice Burroughs (1875-1950), American author of Tarzan fame The Burroughs Corporation began in 1886 as the American Arithmometer Company in St. ... Control Data Corporation, or CDC, was one of the pioneering supercomputer firms. ... Cray Inc. ... Honeywell (NYSE: HON) is a major American multinational corporation that produces electronic control systems and automation equipment. ... Big Blue redirects here. ... Texas Instruments (NYSE: TXN), better known in the electronics industry (and popularly) as TI, is an American company based in Dallas, Texas, USA, renowned for developing and commercializing semiconductor and computer technology. ... This article or section is in need of attention from an expert on the subject. ... Look up cache in Wiktionary, the free dictionary. ... A system of codes directly understandable by a computers CPU is termed this CPUs native or machine language. ... In computer science, an instruction typically refers to a single operation of a processor within a computer architecture. ... The ILLIAC IV was one of the most infamous supercomputers ever, destined to be the last in a series of research machines from the University of Illinois. ... NASA Insignia Listen to this article · (info) This audio file was created from an article revision dated 2005-09-01, and does not reflect subsequent edits to the article. ... Aerial View of Moffett Field and NASA Ames Research Center. ...

Object-Oriented Fortran is an object-oriented extension of Fortran, in which data items can be grouped into objects, which can be instantiated and executed in parallel. It was available for Sun, Iris, iPSC, and nCUBE, but is no longer supported.

Such machine-specific extensions have either disappeared over time or have had elements incorporated into the main standards; the major remaining extension is OpenMP, which is a cross-platform extension for shared memory programming. One new extension, CoArray Fortran, is intended to support parallel programming. OpenMP logo The OpenMP application programming interface (API) supports multi-platform shared memory multiprocessing programming in C/C++ and Fortran on many architectures, including Unix and Microsoft Windows platforms. ... Co-array Fortran, formerly known as F--, is an extension of Fortran 95 for parallel processing created by Robert Numrich and John Reid. ...

Fortran-based languages

Prior to FORTRAN 77, a number of preprocessors were commonly used to provide a friendlier language, with the advantage that the preprocessed code could be compiled on any machine with a standard FORTRAN compiler. Popular preprocessors included FLECS, MORTRAN, Ratfor, and Ratfiv. (Ratfor and Ratfiv, for example, implemented a remarkably C-like language, outputting preprocessed code in standard FORTRAN 66.^[6]) In computer science, a preprocessor is a program that processes its input data to produce output that is used as input to another program. ... Mortran (More Fortran) is an extension of the Fortran programming language used for scientific computation. ... Ratfor (short for RATional FORtran) is a programming language implemented as a preprocessor for Fortran. ... Ratfiv is an enhanced version of the Ratfor programming language, a preprocessor for Fortran designed to give it C-like capabilities. ... C is a general-purpose, procedural, imperative computer programming language developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system. ...

The Fortran-95 Standard includes an optional Part 3 which defines an optional conditional compilation capability. This capability is often referred to as "CoCo".

Many Fortran compilers have integrated subsets of the C preprocessor into their systems. The C preprocessor (cpp) is the preprocessor for the C programming language. ...

SIMSCRIPT is an application specific Fortran preprocessor for modeling and simulating large discrete systems. SIMSCRIPT is a free-form, English-like general-purpose simulation language produced by Harry Markowitz et al of Rand Corp in 1963. ...

F was designed to be a clean subset of Fortran 95 that attempted to remove the redundant, unstructured, and deprecated features of Fortran, such as the EQUIVALENCE statement. F is a compiled, structured, array programming language especially well suited to education and scientific computing. ...

Criticisms and rebuttals

Arcane syntax

As what was essentially a first attempt at designing a high-level language, Fortran's syntax is sometimes regarded as archaic by programmers familiar with subsequently developed languages such as C. Fortran has stayed abreast of such advances, however, and contemporary versions have attempted to supersede and deprecate such syntax in favor of more robust and transparent syntax. A high-level programming language is a programming language that, in comparison to low-level programming languages, may be more abstract, easier to use, or more portable across platforms. ... C is a general-purpose, procedural, imperative computer programming language developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system. ...

Early FORTRAN syntax (prior to Fortran 90) did not in general treat blanks as significant, which made writing robust and efficient lexical analyzers for Fortran very difficult. Subsequent developments such as free-form source have largely resolved these issues. This is not considered significant because the lexical analyzer is a tiny part of a compiler. Lexical analysis is the processing of an input sequence of characters (such as the source code of a computer program) to produce, as output, a sequence of symbols called lexical tokens, or just tokens. For example, lexers for many programming languages convert the character sequence 123 abc into two tokens...

A language tailored to "specialists"

Historical versions of Fortran could rightly be criticized for arbitrary conventions such as implicit typing and fixed-form source input, which together with a paucity of block structures could allow careless or obfuscated programming practices. However, modern Fortran has overcome such issues. Since its introduction, Fortran has been tuned to scientific and numerical work. Fortran 95 provides concise statements for applying mathematical operations directly to entire arrays, which not only improves program readability but also assists the compiler in vectorizing operations. As another example, from its earliest days Fortran provided full support for complex numbers (used, e.g., in the computation of Fourier transforms and in power engineering calculations), a feature not supported by the C Standard until the advent of the ISO/IEC 9899:1999 ("C99") standard. Vectorization, in computer science, is a the process of converting an algorithm from a scalar implementation, which does an operation one pair of operands at a time, to a vector process where a single instruction can refer to a vector (series of adjacent values). ... In mathematics, the Fourier transform is a certain linear operator that maps functions to other functions. ... This article or section does not cite its references or sources. ... C is a general-purpose, procedural, imperative computer programming language developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system. ...

For these reasons, while Fortran is seldom used outside of scientific and engineering numerical work, it remains the language of choice for high-performance numerical computing. It is also simple for non-programmers, particularly those with a mathematical or technical background, to learn how to write efficient, numerically robust code in Fortran.

C/C++ is 'just as fast'

Fortran was designed to create fast executable code for scientific programming. One reason for this is that compiled Fortran programs were intended to be comparable in performance to hand-written machine code from the start. In scientific computing, this means that efficient array processing is of critical concern. Few other languages treat arrays, especially multi-dimensional arrays, as cleanly and simply as Fortran does.

In particular, Fortran data items are not allowed to alias one another, except in very well-defined and explicit situations. This assists Fortran compilers in generating very efficient code, by default, compared to pointer-intensive languages. On the other hand, explicit use of certain C features, such as the C99 restrict attribute can mitigate some of the performance problems of C. In computing, aliasing is a term that generally means that one variable or some reference, when changed, has an indirect (usually unexpected) effect on some other data. ... The C Programming Language, Brian Kernighan and Dennis Ritchie, the original edition that served for many years as an informal specification of the language The C programming language is a low_level standardized programming language developed in the early 1970s by Ken Thompson and Dennis Ritchie for use on the UNIX...

Fortran 95 is slower than FORTRAN 77

Most programs in FORTRAN 77 are valid in Fortran 95, or require only minor changes. The new Fortran features often allow the programmer to express his or her intentions more precisely and explicitly, affording the compiler greater opportunity for optimization. Any observed slowdown resulting from rewriting a FORTRAN 77 program in Fortran 95 is usually caused by improper usage of Fortran 95 features.

Fortran programs require static storage allocation

It is a common misconception that Fortran requires static storage allocation for all local variables. Both the FORTRAN 66 and FORTRAN 77 Standards allowed, but did not require, a fully static implementation. FORTRAN 77 introduced the SAVE statement to allow a programmer to state explicitly which variables are required to retain their values when they go out of scope. Fortran 90 introduced dynamic storage, automatic variables and RECURSIVE procedures. In a recursive procedure, non-SAVEd local variables must be unique for each active instance of the procedure. In computer science, there are several precise meanings of static variable, depending upon the use and context. ... In computer science, a local variable is a variable that is given local scope. ... In computer programming in general, a scope is an enclosing context. ... A Sierpinski triangle —a confined recursion of triangles to form a geometric lattice. ...

Code examples

The sample programs can be compiled and run with any standard Fortran compiler (see the end of this article for lists of compilers). Most modern Fortran compilers expect a file with a .f or .for extension (for FORTRAN 66 or FORTRAN 77 fixed-form source, although the FORTRAN 66 dialect may have to be selected specifically with a command-line option) or .f90/.f95 extension (for Fortran 90/95 free-form source, respectively).

The following sample programs can be compiled and run with any standard Fortran compiler (see the end of the main Fortran article for lists of compilers). ...

FORTRAN jokes

For a programming language with a half-century legacy, FORTRAN not surprisingly has accumulated its share of jokes and folklore.

Standard jokes

• "GOD is REAL unless declared INTEGER."

• Joke, circa 1980 (following the standardization of FORTRAN 77): "Q: What will the scientific programming language of the year 2000 look like? ... A: Nobody knows, but its name will be FORTRAN."

• A good FORTRAN programmer can write FORTRAN code in any language.

• Computer Science without FORTRAN and COBOL is like birthday cake without ketchup and mustard.

From the historical record

• FORTRAN, the infantile disorder, by now nearly 20 years old, is hopelessly inadequate for whatever computer application you have in mind today: it is now too clumsy, too risky, and too expensive to use. Edsger W. Dijkstra, circa 1970.

• "The sooner the world forgets that FORTRAN ever existed, the better." (imputed to Joseph Weizenbaum)

• "The primary purpose of the DATA statement is to give names to constants; instead of referring to pi as 3.141592653589793 at every appearance, the variable PI can be given that value with a DATA statement and used instead of the longer form of the constant. This also simplifies modifying the program, should the value of pi change." —Early FORTRAN manual for Xerox Computers^[7]

• "Consistently separating words by spaces became a general custom about the tenth century A.D., and lasted until about 1957, when FORTRAN abandoned the practice." —Sun FORTRAN Reference Manual

• "People are very flexible and learn to adjust to strange surroundings — they can become accustomed to read Lisp and Fortran programs, for example." —Art of PROLOG, Leon Sterling and Ehud Shapiro, MIT Press

• "Warning: Go directly to Jail. Do not pass GO. Do not collect $200." - Easter egg in the SDS/Xerox Sigma 7 FORTRAN compiler, when the statement GO TO JAIL was encountered. The message is from a Chance card in Monopoly.

Joseph Weizenbaum. ... The first easter egg. ... Scientific Data Systems, or SDS, was a computer company founded in September 1961 by Max Palevsky, a veteran of Packard Bell and Bendix, along with eleven other computer scientists. ... Xerox Corporation (NYSE: XRX) is an American document management company, which manufactures and sells a range of color and black-and-white printers, multifunction systems, photo copiers, digital production printing presses, and related consulting services and supplies. ... The text on each card is as follows: ADVANCE TO GO (COLLECT $200) ADVANCE TO ILLINOIS AVE. ADVANCE TOKEN TO NEAREST UTILITY. IF UNOWNED you may buy it from bank. ... Monopoly is the best-selling commercial board game in the world. ...

References in popular culture

• In the pilot episode of the Futurama series, the robot Bender drinks a bottle of Olde FORTRAN Malt Liquor (alluding to "Olde English" malt liquor)

• Computer folklore has attributed, incorrectly, the loss of an early U.S.A. rocket to an error in a Fortran program. For example, Recall the first American space probe to Venus, reportedly lost because Fortran cannot recognize a missing comma in a DO statement ... Hoare, C. A. R.. Hints on Programming Language Design. in (October 1973) Sigact/Sigplan Symposium on Principles of Programming Languages., reprinted in Horowitz. Programming Languages, A Grand Tour, 3rd ed.. See http://catless.ncl.ac.uk/Risks/9.54.html#subj1.

Futurama is an American animated sitcom created by Matt Groening (creator of The Simpsons) and David X. Cohen for the Fox Network. ... ASIMO, a humanoid robot manufactured by Honda. ... Bender Bending Rodríguez, more commonly known as Bender is a main character in the popular animated television series Futurama. ... This article or section may contain original research or unverified claims. ...

References

Textbooks

• Chapman, Stephen J. (2003). Fortran 90/95 for Scientists and Engineers, 2nd ed., McGraw-Hill. ISBN 0-07-282575-8.
• Ellis, T. M. R.; Ivor R. Phillips, Thomas M. Lahey (1994). Fortran 90 Programming, 1st ed., Addison Wesley. ISBN 0-201-54446-6.
• McCracken, Daniel D. (1961). A Guide to Fortran Programming. Wiley.
• McCracken, Daniel D. (1965). A Guide to Fortran IV Programming. Wiley.
• Metcalf, Michael; John Reid, Malcolm Cohen (2004). Fortran 95/2003 Explained. Oxford University Press.
• Nyhoff, Larry; Sanford Leestma (1995). FORTRAN 77 for Engineers and Scientists with an Introduction to Fortran 90, 4th ed., Prentice Hall. ISBN 0-13-363003-X.

"Core" language standards

• ANSI X3.9-1966. USA Standard FORTRAN, informally known as FORTRAN 66, American National Standards Institute.
• ANSI X3.9-1978. American National Standard – Programming Language FORTRAN, also known as ISO 1539-1980, informally known as FORTRAN 77, American National Standards Institute.
• ANSI X3.198-1992 (R1997). American National Standard – Programming Language Fortran Extended, informally known as Fortran 90, American National Standards Institute.
• ISO/IEC 1539-1:1997. Information technology – Programming languages – Fortran – Part 1: Base language, informally known as Fortran 95. There are a further two parts to this standard. Part 1 has been formally adopted by ANSI.
• ISO/IEC 1539-1:2004. Information technology – Programming languages – Fortran – Part 1: Base language, informally known as Fortran 2003.

ISO has many meanings: Iso is the stem of the Latin transliteration of the Greek word ίσος (ísos, meaning equal). The iso- prefix in English derives from this and means equality or similarity. ...

Related standards

• Wilfried Kneis (October 1981). "Draft standard Industrial Real-Time FORTRAN". ACM SIGPLAN Notices 16 (7): 45–60.
• MIL-STD-1753. DoD Supplement to X3.9-1978. U. S. Government Printing Office.
• POSIX 1003.9-1992. POSIX FORTRAN 77 Language Interface – Part 1: Binding for System Application Program Interface [API]. The Institute of Electrical and Electronics Engineers, Inc.

Industrial Real-Time Fortran (IRTF) was developed in the 1970s to augment the Fortran languge with library bindings useful for process and device control, and I/O. Also included in IRTF was a set of bit-manipulation functions which were eventually incorporated into MIL_STD-1753 for Fortran-77, and later...

External links

History

• "The FORTRAN Automatic Coding System" by Backus, et al., Proceedings of the WJCC (Western Joint Computer Conference), Los Angeles, California, February, 1957.
  describes the design and implementation of the first FORTRAN compiler by the IBM team.
• Historic Documents in Computer Science — Early Fortran manuals
  • The FORTRAN Automatic Coding System for the IBM 704 EDPM (PDF file) — The very first Fortran manual, by John Backus et al. and dated "15 October 1956" (Attests to the origin of the name FORTRAN as deriving from The IBM Mathematical Formula Translating System. And note that the front cover page refers to the language as Fortran, not FORTRAN.)
• History of FORTRAN and FORTRAN II at the Computer History Museum
• John Backus (August 1978). "The History of FORTRAN I, II, and III". ACM SIGPLAN Notices 13 (8): 165–180.
• History of programming languages
• FORTRAN at HOPL site
• "The IBM CE Manual for FORTRAN I, II, and 709", from 1959
• Systems Manual for 704 FORTRAN and 709 FORTRAN - IBM, April, 1960. In-depth internals of an early FORTRAN compiler. It gives a presentation of "basic blocks" for code optimization. It also spells FORTRAN, the acronym, in the text itself, as "Fortran".
• "A History of Language Processor Technology in IBM", by F.E. Allen, IBM Journal of Research and Development, v.25, no.5, September 1981.

It has been suggested that the section History from the article Programming language be merged into this article or section. ...

Standards

• JTC1/SC22/WG5 — The ISO/IEC Fortran Working Group

Tutorials

• Unit 7.1 FORTRAN 77 — Part of ASPIRE's "Computational Science Textbook" project
• Unit 7.2 Fortran 90 — Part of ASPIRE's "Computational Science Textbook" project
• User Notes on FORTRAN Programming (UNFP) — "An open cooperative practical guide"
• Donn Seeley (Dec./Jan. 2004/2005). "How Not to Write FORTRAN in Any Language". ACM Queue 2 (9).

References

• Programming:Fortran overview from Wikibooks
• IBM XL Fortran 6.1 Language Reference
• Page, Clive G. (January 1988). The Professional Programmer's Guide to FORTRAN 77, 1st ed., Hyperion Books. ISBN 0-273-02856-1.
• Fortran 90, 95, 2003, 77 Information Resources at Information Services and Systems, King's College London
• Fortran 77 — FORTRAN 77 documentation

Wikibooks logo Wikibooks, previously called Wikimedia Free Textbook Project and Wikimedia-Textbooks, is a wiki for the creation of books. ...

Code repositories

• FLIB2C (Fortran Library to C) at MYCPLUS — "A tool to create header files that provide a simple and easy-to-use interface between FORTRAN (library) routines and C"
• Fortran 90 Software Repository at NAG (Numerical Algorithms Group)
• fUnit - A unit testing framework.
• High-Precision Software Directory at the Computational Research Division of Lawrence Berkeley National Laboratory
• National HPCC Software Exchange at the Department of Computer Science at the University of Tennessee at Knoxville
• Netlib Repository at the University of Tennessee at Knoxville and Oak Ridge National Laboratory
• Software from Alan J. Miller Logistic Regression; TOMS algorithms; Special code for F and NAS compilers; Miscellaneous other code; Applied Statistics Algorithms. Also a list Some other useful web sites.
• Visual Numerics (developers of IMSL)

Free (open-source) compilers

• g77: "g77 is a free Fortran 77 compiler...now integrated into the GNU Compiler Collection (GCC)." Note: GCC, as of version 4.0, now includes GFortran as the default Fortran compiler in lieu of g77.
• g95: "The goal of the g95 project is to create a free, open source Fortran 95 compiler and runtime libraries." Note: Once an open, collaborative effort, the project has now reverted to the exclusive control of the original g95 project creator.
• GFortran: "The GNU Fortran 95 compiler, part of GCC." Distributed as part of GCC as of GCC 4.0, GFortran is likely to become the de facto "standard" Fortran compiler (much as g77 was through GCC 3.4.6).
  • Official GCC page, from which GCC (with GFortran) can be downloaded
  • GCC and GFortran online documentation
• High Performance Computing for Mac OS X — Fortran compilers for Mac OS X.
• Open Research Compiler for Itanium(TM) Processor Family
• Open64 is a suite of optimizing compiler development tools for Intel Itanium(TM) systems running Linux. The Open64 project is the continuation of the SGI Pro64(TM)
• Open Watcom: "A joint effort between SciTech Software Inc, Sybase and the Open Source development community to maintain and enhance the Watcom C/C++ and Fortran cross compilers and tools."

The GNU Compiler Collection (usually shortened to GCC) is a set of programming language compilers produced by the GNU Project. ... GFortran is the name of the GNU Fortran 95 compiler, which is part of the GNU Compiler Collection. ... The GNU Compiler Collection (usually shortened to GCC) is a set of programming language compilers produced by the GNU Project. ...

Free (not open-source) compilers

• F is a free Fortran 95 subset compiler. F is a compiled, structured, array programming language especially well suited to education and scientific computing.
• Intel Fortran Compiler for Linux for personal, non-commercial, use
• Salford Personal edition for Windows
• Sun Studio Fortran 95 From Sun Microsystems; compiles optimized and parallelized code for Solaris OS SPARC and x86/x64 platforms, and Linux OS x86/x64 platforms.

F is a compiled, structured, array programming language especially well suited to education and scientific computing. ... Microsoft Windows is the name of several families of operating systems by Microsoft. ... Sun Microsystems, Inc. ... Look up Solaris in Wiktionary, the free dictionary. ... Sun UltraSPARC II Microprocessor Sun UltraSPARC T1 (Niagara 8 Core) SPARC (Scalable Processor ARChitecture) is a pure big-endian RISC microprocessor instruction set architecture originally designed in 1985 by Sun Microsystems. ... x86 or 80x86 is the generic name of a microprocessor architecture first developed and manufactured by Intel. ... x64 is Microsoft Corporations marketing designation for the Advanced Micro Devices AMD64 and Intel EM64T 64-bit Instruction Set Extensions to the x86 architecture, which were substantially similar as of 2004. ... Linux, or GNU/Linux, refers to any Unix-like computer operating system which uses the Linux kernel. ... x86 or 80x86 is the generic name of a microprocessor architecture first developed and manufactured by Intel. ... x64 is Microsoft Corporations marketing designation for the Advanced Micro Devices AMD64 and Intel EM64T 64-bit Instruction Set Extensions to the x86 architecture, which were substantially similar as of 2004. ...

Commercial compilers

• Absoft Corporation
• Apogee SPARC compilers
• Cray Inc
• Fujitsu
• HP Has been sold to Intel
• IBM
• Intel
• Lahey
• NAG
• PathScale
• Portland Group
• Salford Commercial and Academic editions
• SGI

Free graphical libraries/GUI

• f90gl: "f90gl is a public domain implementation of the official Fortran 90 bindings for OpenGL." For Linux, Mac OS X, Solaris, UNIX, Windows. Public domain.
• ftcl: Combining Fortran and Tcl in one program — A Fortran–Tcl/TK interface. Open-source.
• g2 graphical library: "g2 is an easy to use, portable and powerful 2D graphics library." For Linux, Mac OS X, OpenVMS, Solaris, UNIX, Windows. GNU LGPL.
• GrWin Graphics Library: "GrWin Graphics Library is a free graphics routine library for Fortran and C/C++." For Windows. Open-source.
• japi (Java Application Programming Interface): "An open source free software GUI toolkit." For Linux, Mac OS X, Solaris, UNIX, Windows. GNU LGPL.
• Platform Independent Library for Fortran 90/95: "The portable way [for] creating GUIs, doing file IO etc. This library is an attempt to build a platform and compiler independent library for Fortran 9x." For Linux, Mac OS X, UNIX, Windows. GNU LGPL.
• PLplot – a Scientific Plotting Library: "PLplot is a library of functions that are useful for making scientific plots." For Linux, Mac OS X, MS-DOS, Unix, Windows. GNU LGPL.

GNU logo The GNU Lesser General Public License (formerly the GNU Library General Public License) is an FSF approved Free Software license designed as a compromise between the GNU General Public License and simple permissive licenses such as the BSD license and the MIT License. ... GNU logo The GNU Lesser General Public License (formerly the GNU Library General Public License) is an FSF approved Free Software license designed as a compromise between the GNU General Public License and simple permissive licenses such as the BSD license and the MIT License. ... GNU logo The GNU Lesser General Public License (formerly the GNU Library General Public License) is an FSF approved Free Software license designed as a compromise between the GNU General Public License and simple permissive licenses such as the BSD license and the MIT License. ... GNU logo The GNU Lesser General Public License (formerly the GNU Library General Public License) is an FSF approved Free Software license designed as a compromise between the GNU General Public License and simple permissive licenses such as the BSD license and the MIT License. ...

Proprietary/non-free graphical libraries/GUI

• DISLIN: "DISLIN is a high-level plotting library for displaying data as curves, polar plots, bar graphs, pie charts, 3D-color plots, surfaces, contours and maps." For DOS, Linux, Mac OS X, OpenVMS, UNIX, Windows. "Free for non-commercial use" (but not free).
• SansGUI: Requires Microsoft Visual C/C++ 6.0+ or Compaq Visual Fortran 6.1+. For Windows.
• Winteracter: "The Fortran 9x GUI Toolset." For Linux, Mac OS X, Windows.

This article is about free software as defined by the sociopolitical free software movement; for information on software distributed without charge, see freeware. ...

Testing Frameworks

• fUnit - a unit testing framework.

Miscellaneous

Wikibooks has a book on the topic of

Fortran

• comp.lang.fortran on Usenet
• Fortran Open Directory category

Image File history File links Wikibooks-logo-en. ... Wikibooks logo Wikibooks, previously called Wikimedia Free Textbook Project and Wikimedia-Textbooks, is a wiki for the creation of books. ...

Notes

1. ^ The names of earlier versions of the language through FORTRAN 77 were conventionally spelled in all-caps (FORTRAN 77 was the last version in which the use of lowercase letters in keywords was strictly nonstandard). The capitalization has been dropped in referring to newer versions beginning with Fortran 90. The official language standards now refer to the language as "Fortran." Because the capitalization (or lack thereof) of the word FORTRAN was never 100% consistent in actual usage, and because many hold impassioned beliefs on the issue, this article, rather than attempt to be normative, adopts the convention of using the all-caps FORTRAN in referring to versions of FORTRAN through FORTRAN 77 and the title-caps Fortran in referring to versions of Fortran from Fortran 90 onward. This convention is reflected in the capitalization of FORTRAN in the ANSI X3.9-1966 (FORTRAN 66) and ANSI X3.9-1978 (FORTRAN 77) standards and the title caps Fortran in the ANSI X3.198-1992 (Fortran 90) standard.
2. ^ Since FORTRAN 77, which introduced the CHARACTER data type.
3. ^ Since FORTRAN II (1958).
4. ^ Note: It is commonly believed that this statement corresponded to a three-way branch instruction on the IBM 704. This is not true, the 704 branch instructions all contained only one destination address (e.g., TZE - Transfer AC Zero, TNZ - Transfer AC Not Zero, TPL - Transfer AC Plus, TMI - Transfer AC Minus). The machine (and its successors in the 700/7000 series) did have a three-way skip instruction (CAS - Compare AC with Storage), which was probably the origin of this belief, but using this instruction to implement the IF would consume 4 instruction words, require the constant Zero in a word of storage, and take 3 machine cycles to execute; using the Transfer instructions to implement the IF could be done in 1 to 3 instruction words, required no constants in storage, and take 1 to 3 machine cycles to execute. An optimizing compiler like FORTRAN would most likely select the more compact and usually faster Transfers instead of the Compare (use of Transfers also allowed the FREQUENCY statement to optimize IFs, which could not be done using the Compare). Also the Compare considered -0 and +0 to be different values while the Transfer Zero and Transfer Not Zero considered them to be the same.
5. ^ The FREQUENCY statement in FORTRAN was used originally and optionally to give branch probabilities for the three branch cases of the Arithmetic IF statement to bias the way code was generated and order of the basic blocks of code generated, in the global optimisation sense, were arranged in memory for optimality. The first FORTRAN compiler used this weighting to do a Monte Carlo simulation of the run-time generated code at compile time. It was very sophisticated for its time. This technique is documented in the original article in 1957 on the first FORTRAN compiler implementation by J. Backus, et al. Many years later, the FREQUENCY statement had no effect on the code, and was treated as a comment statement, since the compilers no longer did this kind of compile-time simulation. Below is a part of the 1957 paper, "The FORTRAN Automatic Coding System" by Backus, et al., with this snippet on the FREQUENCY statement and its use in a compile-time Monte Carlo simulation of the run-time to optimise the code generated. Quoting ...

   The fundamental unit of program is the basic block; a basic block is a stretch of program which has a single entry point and a single exit point. The purpose of section 4 is to prepare for section 5 a table of predecessors (PRED table) which enumerates the basic blocks and lists for every basic block each of the basic blocks which can be its immediate predecessor in flow, together with the absolute frequency of each such basic block link. This table is obtained by an actual "execution" of the program in Monte-Carlo fashion, in which the outcome of conditional transfers arising out of IF-type statements and computed GO TO'S is determined by a random number generator suitably weighted according to whatever FREQUENCY statements have been provided. Standards are produced by many organizations, some for internal usage only, others for use by a groups of people, groups of companies, or a subsection of an industry. ... The IBM 700/7000 series was a series of incompatible large scale (mainframe) computer systems made by IBM through the 1950s and early 1960s. ... Monte Carlo methods are a widely used class of computational algorithms for simulating the behavior of various physical and mathematical systems. ... Monte Carlo methods are a widely used class of computational algorithms for simulating the behavior of various physical and mathematical systems. ... In computing, a basic block is a straight-line piece of code without any jumps or jump targets in the middle; jump targets, if any, start a block, and jumps end a block. ...

6. ^ This is not altogether surprising, as Brian Kernighan, one of the co-creators of Ratfor, is also co-author of The C Programming Language.
7. ^ Prior to FORTRAN 77, which introduced the PARAMETER statement (the preferred method of defining constants), the DATA statement was the conventional way to define constants, although this statement merely specified initial values and did not prevent the corresponding variables from being modified (as by regular assignment statements).