FACTOID # 10: The total number of state executions in 2005 was 60: 19 in Texas and 41 elsewhere. The racial split was 19 Black and 41 White.

 Home Encyclopedia Statistics States A-Z Flags Maps FAQ About

 WHAT'S NEW RELATED ARTICLES People who viewed "FORTRAN" also viewed:

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

(* = Graphable)

Encyclopedia > FORTRAN
Paradigm: The Fortran Automatic Coding System for the IBM 704 (October 15, 1956), the first Programmer's Reference Manual for Fortran multi-paradigm: procedural, imperative, structured, object-oriented 1957 John W. Backus John W. Backus & IBM strong, static Absoft, GFortran, G95, Intel, Lahey/Fujitsu, Open Watcom, Pathscale, PGI, Silverfrost, Sun, XL Fortran, others ALGOL 58, PL/I

An IBM 704 mainframe (image courtesy of LLNL)
FORTRAN code on a punch card, showing the specialized uses of columns 1-5, 6 and 73-80.

While the community was skeptical that this new method could possibly out-perform hand-coding, it reduced the amount of programming statements necessary to operate a machine by a factor of 20, and quickly gained acceptance. Said creator John Backus during a 1979 interview with Think, the IBM employee magazine, "Much of my work has come from being lazy. I didn't like writing programs, and so, when I was working on the IBM 701 (an early computer), writing programs for computing missile trajectories, I started work on a programming system to make it easier to write programs," http://www.msnbc.msn.com/id/17704662/

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 = âˆ’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. 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 IBMâ€™s early computers, and the worldâ€™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. ... In computing, optimization is the process of modifying a system to make some aspect of it work more efficiently or use fewer resources. ...

### 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 does not adequately 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

A FORTRAN coding form, formerly printed on paper and intended to be used by programmers to prepare programs for punching onto cards by card punch operators. Now obsolete.

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. Image File history File links Size of this preview: 800 Ã— 507 pixel Image in higher resolution (1573 Ã— 997 pixel, file size: 54 KB, MIME type: image/png) Screen shot of PDF FORTRAN Coding Form inspired by an old IBM form. ... Image File history File links Size of this preview: 800 Ã— 507 pixel Image in higher resolution (1573 Ã— 997 pixel, file size: 54 KB, MIME type: image/png) Screen shot of PDF FORTRAN Coding Form inspired by an old IBM form. ... IBM 029 keypunch. ...

### 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 IBM 7094. Year 1961 (MCMLXI) was a common year starting on Sunday (link will display full calendar) of the Gregorian 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. ... The IBM 7094 the fourth member of the most popular family of IBMs large second-generation transistorized mainframe computers and was designed for large-scale scientific and technological applications. The first 7094 installation was in September 1962. ...

### 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:

• Block `IF` and `END IF` statements, with optional `ELSE` and `ELSE IF` clauses, to provide improved language support for structured programming
• DO loop extensions, including parameter expressions, negative increments, and zero trip counts
• `OPEN`, `CLOSE`, and `INQUIRE` statements for improved I/O capability
• Direct-access file I/O
• `IMPLICIT` statement
• `CHARACTER` data type, with vastly expanded facilities for character input and output and processing of character-based data
• `PARAMETER` statement for specifying constants
• `SAVE` statement for persistent local variables
• Generic names for intrinsic functions
• A set of intrinsics (`LGE, LGT, LLE, LLT`) for lexical comparison of strings, based upon the ASCII collating sequence.
(ASCII functions were demanded by the U. S. Department of Defense, in their conditional approval vote.)

In this revision of the standard, a number of features were removed or altered in a manner that might invalidate previously-standard-conforming programs. (Removal was the only allowable alternative to X3J3 at that time, since the concept of "deprecation" was not yet available for ANSI standards.) While most of the 24 items in the conflict list (See Appendix A2 of X3.9-1978) addressed loopholes or pathological cases permitted by the previous standard but rarely used, a small number of specific capabilities were deliberately removed, such as: Structured programming can be seen as a subset or subdiscipline of procedural programming, one of the major programming paradigms. ... Image:ASCII fullsvg There are 95 printable ASCII characters, numbered 32 to 126. ... This article does not cite any references or sources. ...

• Hollerith constants and Hollerith data, such as:
GREET = 12HHELLO THERE!
• Reading into a H edit (Hollerith field) descriptor in a FORMAT specification.
• Overindexing of array bounds by subscripts.
`DIMENSION A(10,5)`
`Y= A(11,1)`
• Transfer of control into the range of a DO loop (also known as "Extended Range").

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. This article does not cite any references or sources. ...

• `DO WHILE` and `END DO` statements
• `INCLUDE` statement
• `IMPLICIT NONE` variant of the `IMPLICIT` statement
• Bit manipulation intrinsic functions, based on similar functions included in Industrial Real-Time Fortran (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. Bit manipulation is the act of algorithmically manipulating bits or other pieces of data shorter than byte. ... 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. ... POSIX or Portable Operating System Interface[1] is the collective name of a family of related standards specified by the IEEE to define the application programming interface (API) for software compatible with variants of the Unix operating system. ...

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
• Identifiers up to 31 characters in length
• Ability to operate on arrays (or array sections) as a whole, thus greatly simplifying math and engineering computations.
• whole, partial and masked array assignment statements and array expressions, such as   `X(1:N)=R(1:N)*COS(A(1:N)))`
• `WHERE` statement for selective array assignment)
• array-valued constants and expressions,
• user-defined array-valued functions and array constructors.
• `RECURSIVE` procedures
• 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.
• A vastly improved argument-passing mechanism, allowing interfaces to be checked at compile time
• User-written interfaces for generic procedures
• Derived/abstract data types
• New data type declaration syntax, to specify the data type and other attributes of variables
• 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
• Structured looping constructs, with an `END DO` statement for loop termination, and `EXIT` and `CYCLE` statements for "breaking out" of normal `DO` loop iterations in an orderly way
• `SELECT` . . . `CASE` construct for multi-way selection
• 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. ... A visual form of recursion known as the Droste effect. ... It has been suggested that this article or section be merged into Modularity (programming). ... 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 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. ...

##### Obsolescence & Deletions

Unlike the previous revision, Fortran 90 did not delete any features. (Appendix B.1 says, "The list of deleted features in this standard is empty.") Any standard-conforming FORTRAN 77 program is also standard-conforming under Fortran 90, and either standard should be usable to define its behavior.

A small set of features were identified as "obsolescent" and expected to be removed in a future standard.

Obsolescent feature Example Status / 95
Arithmetic IF-statement `    IF (X) 10, 20, 30`
Non-integer DO parameters or control variables `    DO 9, X= 1.7, 1.6, -0.1` Deleted
Shared DO-loop termination or
termination with a statement
other than END DO or CONTINUE
`    DO 9, J= 1, 10`

`        DO 9, K= 1, 10 9   L= J + K`

Branching to END IF

from outside a block

`66  GO TO 77 ; . . .`

`    IF (E) THEN ;     . . . 77  END IF`

Deleted
Alternate return `    CALL SUBR( X, Y *100, *200 )`
PAUSE statement `    PAUSE 600` Deleted
ASSIGN statement
and assigned GO TO statement
`100  . . .`

`    ASSIGN 100 TO H     . . .     GO TO H . . .`

Deleted
Assigned FORMAT specifiers `    ASSIGN F TO 606` Deleted
H edit descriptors `606 FORMAT ( 9H1GOODBYE. )` Deleted
Computed GO TO statement `    GO TO (10, 20, 30, 40) index` (Obso.)
Statement functions `    FOIL( X, Y )= X**2 + X*Y + Y**2` (Obso.)
DATA statements
among executable statements
`    X= 27.3`

`    DATA A, B, C / 5.0, 12.0. 13.0 /     . . .`

(Obso.)
CHARACTER* form of CHARACTER declaration `    CHARACTER*8 STRING   ! Use CHARACTER(8)` (Obso.)
Assumed character length functions
Fixed form source code * Column 1 contains * or ! or C for comments.
C       Column 6 for continuation.

### 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, 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.) â€œISOâ€ redirects here. ... 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. ...

Another important supplement to Fortran 95 was the ISO technical report TR-15580: Floating-point exception handling, informally known as the IEEE TR. This specification defined support for IEEE floating-point arithmetic and floating point exception handling. â€œISOâ€ redirects here. ... 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. ...

#### Conditional Compilation and Varying length strings

In addition to the mandatory "Base language" (defined in ISO/IEC 1539-1 : 1997), the Fortran 95 language also includes two optional modules:

• Varying character strings (ISO/IEC 1539-2 : 2000)
• Conditional compilation (ISO/IEC 1539-3 : 1998)

which, together, comprise the multi-part International Standard (ISO/IEC 1539).

According to the standards developers, "the optional parts describe self-contained features which have been requested by a substantial body of users and/or implementors, but which are not deemed to be of sufficient generality for them to be required in all standard-conforming Fortran compilers." Nevertheless, if a standard-conforming Fortran does provide such options, then they "must be provided in accordance with the description of those facilities in the appropriate Part of the Standard."

### 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 filePDF or `gzip`ped PostScript file. â€œISOâ€ redirects here. ... â€œPDFâ€ redirects here. ...

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 (incorporating TR 15581), 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 (incorporating TR 15580).
• 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. ... This article or section does not cite any references or sources. ... 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 C, C++, D, and other C-like 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, block structured, 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 filePDF (24.2 KiB). Co-array Fortran, formerly known as F--, is an extension of Fortran 95 for parallel processing created by Robert Numrich and John Reid. ... This article is about the unit of information. ... â€œPDFâ€ redirects here. ... A kibibyte (a contraction of kilo binary byte) is a unit of information or computer storage, commonly abbreviated KiB (never kiB). 1 kibibyte = 210 bytes = 1,024 bytes The kibibyte is closely related to the kilobyte, which can be used either as a synonym for kibibyte or to refer to...

### The legacy of FORTRAN

Since Fortran has been in use 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 and 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 example of 500 mb geopotential height prediction from a numerical weather prediction model Numerical weather prediction is the science of predicting the weather using mathematical models of the atmosphere. ... 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 complement the information obtained by actual chemical experiments, predict hitherto unobserved chemical phenomena, and solve related problems. ... Quantum chromodynamics (abbreviated as QCD) is the theory of the strong interaction (color force), a fundamental force describing the interactions of the quarks and gluons found in hadrons (such as the proton, neutron or pion). ... Spec may refer to: spec is a music video or commercial which its creator produces at his own expense to improve his showreel in order to get a paid job. ...

## 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. ...

For more details on this topic, see Fortran language features.

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. NIST logo The National Institute of Standards and Technology (NIST, formerly known as The National Bureau of Standards) is a non-regulatory agency of the United States Department of Commerceâ€™s Technology Administration. ...

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 Heating Specialties Company Stock Certificate dated 1924 signed by Mark C. Honeywell - courtesy of Scripophily. ... For other uses, see IBM (disambiguation) and Big Blue. ... 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. ... UNIVAC serves as the catch-all name for the American manufacturers of the lines of mainframe computers by that name, which through mergers and acquisitions underwent numerous name changes. ... 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. ... This article is about the American space agency. ... Aerial View of Moffett Field and NASA Ames Research Center. ...

Object-Oriented Fortran was 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. 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. ...

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 (Open Multi-Processing) is an application programming interface (API) that 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, block structured, 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". The C preprocessor (cpp) is the preprocessor for the C programming language. ...

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. ...

## 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).

For more details on this topic, see Fortran code examples.

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 quotations

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

### From the historical record

• God is Real, unless declared Integer.[2] J.Allan Toogood, FORTRAN programmer. In FORTRAN, undeclared variables are typed according to their first letter, so "God" would be a real number.
• 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 Dijkstra, circa 1970.
• "The sooner the world forgets that FORTRAN ever existed, the better." (imputed to Joseph Weizenbaum)
• "95 percent of the people who programmed in the early years would never have done it without Fortran." - Ken Thompson, circa 2005 [7]
• "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[8]
• "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.

Edsger Dijkstra Edsger Wybe Dijkstra (Rotterdam, May 11, 1930 â€“ Nuenen, August 6, 2002; IPA: ) was a Dutch computer scientist. ... Joseph Weizenbaum. ... Kenneth Lane Thompson (born February 4, 1943), commonly referred to as Ken Thompson (or simply Ken in hacker circles), is an American pioneer of computer science notable for his work with the B programming language and his shepherding the UNIX and Plan 9 from Bell Labs operating systems. ... 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) (name pronounced ) is a global 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

• Computer folklore has incorrectly attributed the loss of the Mariner I space probe to a typographical 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 ..." [9].
• In 1982, 10,000 Maniacs released a song named "Planned Obsolescence" that includes the repeated line - "Science [is] truth for life, in Fortran tongue the answer".

This article is about the television series. ... For other uses, see robot (disambiguation). ... â€œBenderâ€ redirects here. ... This article does not cite any references or sources. ... Launch of Mariner 1 Mariner 1 was the first spacecraft of the Mariner program. ... 10,000 Maniacs is a United States-based alternative rock band, formed in 1981 and active with various line-ups since that time. ...

## FORTRAN Anecdotes

### FORTRAN II on the IBM 1401 and 1460

The IBM 1401 computer, introduced in 1959, supported Fortran by the middle 1960s although the 1401 was intended for decimal business computation and as a primitive printer "server" that would print the contents of magnetic tapes, prepared on much larger systems such as the IBM 7090.

The absolute minimum configuration was supported, for example, at Roosevelt University in Chicago until 1974 (cf. Edward G. Nilges, "Build Your Own .Net Language and Compiler", Apress 2004). This configuration was 8K of 6-bit bytes for RAM and a card reader and punch (cf. Nilges, "Anecdotes", IEEE Transactions on the History of Software, Spring/Summer 1999).

The compiler, as described below, was a series of about 100 small overlay phases (cf. John A. N. Lee, "The Anatomy of a Compiler", Van Nostrand Rheinhold 1968), where a miniature monitor stayed resident in memory to load each phase. These phases were loaded from a card deck of more than 2,000 punched cards (more than two feet long) or from a tape drive (which wasn't available at the Roosevelt University installation).

These overlays would scan and parse a "squozed" (blank-removed: run length encoded) form of the source code to produce statements in an interpretive language at the end of available memory (since the end of memory could not be sensed, it had to be spelled out on a "control card"). The final phase was responsible for interpreting the code.

Despite the primitive Fortran II compiled, which had no strings, the rather complex and flexible FORMAT statement was supported. In addition, another "control" card could specify how many decimals would be supported in floating point format; this feature looked forward to a vastly more flexible feature in today's Mathematica system.

However, for a number of years, the installation at Roosevelt University was deprived of Fortran despite the availability of the compiler "deck". At some point in time in 1970, an IBM customer engineer had "fixed" a bug, thought to result from the absence of special-purpose multiply/divide hardware (for which 1401 customers had to pay extra) by overlaying memory with a jump to a subroutine for multiplication and division.

Unfortunately, on the minimal configuration, this destroyed instructions and never worked for this reason. Roosevelt was paying for multiply and divide, so, when in 1972 the customer engineer's patch was removed, the compiler then worked. It was used for administration, teaching and research until about 1977.

The IBM 1460 (similar to the 1401) also had a Fortran II compiler that resided on tape. It required only that tape drive, a card reader/punch and a printer, i.e. no "work" devices. The IBM 1400 series was a family of mid-range buisiness computers that IBM sold in the early 1960s as a replacement for unit record equipment. ... DDS tape drive. ... A CTR census machine, utilizing a punched card system. ... A computer printer, or more commonly a printer, produces a hard copy (permanent human-readable text and/or graphics) of documents stored in electronic form, usually on physical print media such as paper transparencies]]. Many printers are primarily used as computer peripherals, and are attached by a printer cable to...

The compiler for the 1401 and 1460 was in the form of a multitude of tiny phases, or segments, that were passed over the source program which was held in storage throughout the compile. The first phase read the program from the card reader, numbered the statements, and produced a source listing. The next phases might be something like "copy (and reverse) the program from low storage to high storage, assigning and replacing the names with tokens." The appearance was that the system tape containing the compiler would "blip", the computer would hum for a bit, then the tape would "blip" again and another part of the listing would appear on the printer. The end result was an object deck on the punch, and the program was left in storage and ready to go. It has been suggested that this article or section be merged with Tokenizing. ...

The effect was quite unusual, and was designed to be able to compile the largest possible program with the fewest peripheral devices. It has been suggested that this article or section be merged into Computer hardware. ...

### Letter O considered harmful

During the same Fortran Standards Committee meeting at which the name "FORTRAN 77" was chosen, a technical proposal was somehow smuggled into the official distribution, bearing the title, "Letter O considered harmful". This deceptively simple proposal purported to address the confusion that sometimes arises between the letter "O" and the numeral zero, by eliminating the letter from allowable variable names. However, the method proposed was to eliminate the letter from the character set entirely (thereby retaining 48 as the number of lexical characters, which the colon had increased to 49).

Among the "PRO" arguments was the assertion that this would also promote structured programming, by making it impossible to write a `GO TO` statement. (Troublesome `FORMAT` statements would be eliminated, as well.)

The sole "CON" argument conceded that "this might invalidate some existing programs" but noted that most of these "probably were non-conforming, anyway".

## References

### Textbooks

• Chapman, Stephen J. (2007). Fortran 95/2003 for Scientists and Engineers, 3nd ed., McGraw-Hill. ISBN 978-0-07-319157-7.
• Chapman, Stephen J. (2003). Fortran 90/95 for Scientists and Engineers, 2nd ed., McGraw-Hill. ISBN 0-07-282575-8.
• Chivers, Ian; Jane Sleightholme (2006). Introduction to Programming with Fortran, 1st ed., Springer. ISBN 1-84628-053-2.
• 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. ISBN 0-19-852693-8.
• 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.
• Martínez Baena, Javier; Ignario Requena Ramos, Nicolás Marín Ruiz (2006). Programación estructurada con Fortran 90/95. Universidad de Granada. ISBN 84-338-3923-3.

### "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.

This is an incomplete list of ISO standards. ...

### Related standards

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...

## Notes

1. ^ The names of earlier versions of the language through FORTRAN 77 were conventionally spelled in all-caps (FORTRAN 77 was the 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 `IF`s, 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 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. ... 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, and for other computations. ... Monte Carlo methods are a widely used class of computational algorithms for simulating the behavior of various physical and mathematical systems, and for other computations. ... 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. ^ Lohr, Steve. "John W. Backus, 82, Fortran Developer, Dies", 2007-03-19. Retrieved on 2007-03-20.
8. ^ 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).
9. ^ 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 (and http://catless.ncl.ac.uk/Risks/8.75.html#subj1 for what really happened)

Brian Wilson Kernighan (IPA pronunciation: , the g is silent), (born 1942 in Toronto, Ontario, Canada) is a computer scientist who worked at Bell Labs alongside Unix creators Ken Thompson and Dennis Ritchie and contributed greatly to Unix and its school of thought. ... The C Programming Language, second edition, by Brian Kernighan and Dennis Ritchie, widely regarded to be the authoritative reference on C. The C Programming Language (sometimes referred to as K&R) is a well-known computer science book written by Brian Kernighan and Dennis Ritchie, the latter of whom originally... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... is the 79th day of the year (80th in leap years) in the Gregorian calendar. ...

Results from FactBites:

 Fortran 90 for the Fortran 77 Programmer (269 words) This transition uses the fact that Fortran 77 is a pure subset of Fortran 90. A complete textbook in Swedish on Fortran 90/95 has been prepared, and is available both electronically in a hypertext version and in printed form. Notables in the transition from Fortran 77 to Fortran 90
 Fortran - Wikipedia, the free encyclopedia (4220 words) 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. FORTRAN IV was eventually released in 1962, first for the IBM 7030 ("Stretch") computer, followed by versions for the IBM 7090 and 7094. 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.
More results at FactBites »

Share your thoughts, questions and commentary here