Originally developed by IBM  in the s for scientific and engineering applications, FORTRAN came to dominate this area of programming early on and has been in continuous use for over half a century in computationally intensive areas such as numerical weather predictionfinite element analysiscomputational fluid dynamicscomputational physicscrystallography and computational chemistry.
It is a popular language for high-performance computing  and is used for more info that benchmark and rank the world's fastest supercomputers. Fortran encompasses a lineage of versions, each of which evolved to add extensions to the language while usually retaining compatibility with prior versions.
Successive versions have added support for structured programming and processing of character-based data FORTRAN 77array programmingmodular programming and generic programming Fortran 90high performance Fortran Fortran 95object-oriented programming Fortran and concurrent programming Fortran The capitalization has been dropped in referring to newer versions beginning with Fortran In lateJohn W.
Backus submitted a proposal to his superiors at IBM to develop a more practical alternative to assembly language for programming their IBM mainframe computer. Halcombe Laning and demonstrated in the Laning and Zierler system of This was the first optimizing compilerbecause customers were reluctant to use a high-level programming language unless its What Is Writing could generate code with performance comparable to that of hand-coded assembly language.
While the community was skeptical that this new method could possibly outperform hand-coding, it reduced the number of programming statements necessary to operate a machine by a factor of 20, and quickly gained acceptance. John Backus said during a interview with Thinkthe 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 IBMwriting programs for computing missile trajectories, I started work on a programming system to make it easier to write 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 http://agnix.info/edu-help/dalai-lama-essay-1934.php applications such as electrical engineering.
For these reasons, FORTRAN is considered to be the first widely used programming language supported across a variety of computer architectures. The development of Fortran paralleled the early evolution of compiler technologyand many advances in the theory and design of compilers were specifically motivated by the need to generate efficient code for Fortran programs.
The Monte Carlo technique is documented in Backus et al. The fundamental unit of program is the basic block ; a basic block is a stretch of program which has one entry point and one 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.
Many years later, the FREQUENCY statement had no effect on the code, and was go here as a comment statement, since the compilers no longer did this kind of compile-time simulation.
A similar fate has befallen compiler hints in several other programming languages; for example C 's register keyword. The first FORTRAN compiler reported diagnostic information by halting the program when an error was found and outputting an error code on its console.
That code could be looked up by the programmer in an error messages table in the operator's manual, providing them with a brief description of the problem.
Before the development of disk files, text editors and terminals, programs were most often entered on a keypunch keyboard onto column punched cardsone line to a card. The resulting deck of cards would be fed into a card reader to be compiled. Punched-card codes included no lower-case letters or many special characters, and special versions of the IBM keypunch were offered that would correctly print the re-purposed special characters used in FORTRAN.
Reflecting punched-card input practice, Fortran programs were originally written in a fixed-column format, with the first 72 columns read into twelve bit words. A letter "C" in column 1 caused the entire card to be treated as a comment and ignored by the compiler. Otherwise, the columns of the card were divided into four fields:. Columns 73 to 80 could therefore be used for identification information, such as punching a sequence number or text, which could be used to re-order cards if a stack of cards was How To Write Ln In Fortran 77 though in practice this was reserved for stable, production programs.
An IBM could be used to see more a program deck and add sequence numbers. Some early compilers, e. Later compilers relaxed most fixed-format restrictions, and the requirement was eliminated in the Fortran 90 standard. Within the statement field, whitespace characters blanks were ignored outside a How To Write Ln In Fortran 77 literal. This allowed omitting spaces between tokens for brevity or including spaces within identifiers for clarity.
Note the slight visual difference between a comma and a period.
Miscounts were a problem. The main enhancement was to support procedural programming by allowing user-written subroutines and functions which returned values, with parameters passed by reference. Six new statements were introduced:.
Early computer architectures supported no concept of a stack, How To Write Ln In Fortran 77 when they did directly support subroutine calls, the return location was often stored in one fixed location adjacent to the subroutine code e. Although not specified in Fortran 77, many F77 compilers supported recursion as an option, and the Burroughs mainframesdesigned with recursion built-in, did so by default.
This program, for Heron's formulareads data on a tape reel containing three 5-digit integers A, B, and C click to see more input. There are no "type" declarations available: Since integers are to be processed in this example, the names of the variables link with the letter "I".
If A, B, and C cannot represent the sides of a triangle in plane geometry, then the program's execution will end with an error code of "STOP 1". Otherwise, an output line will be printed showing the input values for A, B, and C, followed by the computed AREA of the triangle as a floating-point number occupying ten spaces along the line of output and showing 2 digits after the decimal point, the.
The compiler could be run from tape, or from a card deck; it used no further tape or disk storage. It kept the program in memory and loaded overlays that gradually transformed it, in place, into executable form, as described by Haines. In this revision of the standard, a number of features were removed or altered in a manner that might invalidate formerly 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. 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.
These features would eventually be incorporated into the Fortran 90 standard. In addition to changing the official spelling from FORTRAN to Fortran, this major revision added many new features to reflect the significant changes in programming practice that had evolved since the standard:.
Unlike the prior revision, Fortran 90 removed no features. A small set of features were identified as article source and expected to be removed in a future standard.
Algorithm: Write an Fortran program to find the sum of the following series 1+3--+99
Nevertheless, Fortran 95 also added a number of extensions, notably from the High Performance Fortran specification:. A number of intrinsic functions were extended for example a dim argument was added to the maxloc intrinsic. In addition, elements of allocatable arrays are contiguous, and aliasing is not an issue for optimization of array references, allowing compilers to generate faster code than in the case of pointers.
This specification defined support for IEEE floating-point arithmetic and floating point exception handling. Enhanced module facilities in Fortran. This report provided sub-modules, which make Fortran modules more similar to Modula-2 modules.
They are similar to Ada private child sub-units. This allows the specification and implementation of a module to be expressed in separate program units, which improves packaging of large libraries, allows preservation of trade secrets while publishing definitive interfaces, and prevents compilation cascades.
The new capabilities include:. The specification adds support for accessing the array descriptor from C and allows ignoring the type and rank of arguments. The next revision of the language Fortran was earlier referred to as Fortran . It is a significant revision and is planned for release in mid .
Although a journal article by the authors of BASIC already described FORTRAN as "old-fashioned",  since Fortran has been in use for several decades there is a vast body of Fortran software in daily use throughout the scientific and engineering communities. Leith called FORTRAN the "mother tongue of scientific computing" adding that its replacement by any other How To Write Ln In Fortran 77 language "may remain a forlorn hope". It is the primary language for some of the most intensive super-computing tasks, such as astronomyweather and climate modelingnumerical linear algebra LAPACKnumerical libraries IMSL and NAGstructural engineeringhydrological modelingoptimizationsatellite simulation and data analysis, computational fluid dynamicscomputational chemistry read article, computational economics and computational physics.
Consequently, a growing fraction of link code is also written in these languages. The precise characteristics and syntax of Fortran 95 are discussed in Fortran 95 language features.
Standards have improved portability. The standard provided a reference syntax and semantics, but vendors continued to provide incompatible extensions. 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. The ideas therein became widely used, and were eventually click at this page into the standard by way of intrinsic inquiry functions.
The widespread now almost universal adoption of the IEEE standard for binary floating-point arithmetic has essentially removed this problem. Access to the computing environment e. 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 standard.
It is now possible and relatively easy to write an entirely portable program in Fortran, even without recourse to a preprocessor. It had an optimizing compiler that was quite good for minicomputers of its time. Fortran 6 or Visual Fortran was licensed to Compaq by Microsoft. They have licensed Compaq Visual Fortran and have provided the Visual Studio 5 environment interface for Compaq v6 up to v6.
Vendors of high-performance scientific computers e. 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.
Such machine-specific extensions have either disappeared over time or have had elements incorporated into the main standards. The major remaining extension is OpenMPwhich is a cross-platform extension for shared memory programming.
One new extension, Coarray Fortranis intended to support parallel programming.
The generic forms "min" and "max" were not a manditory part of the Fortran 77 standard, but are in Fortran In many Fortran 77 codes you will see functions: amax1. Almost all FORTRAN 77 programs read data from external sources such as files or the user's terminal, perform calculations on that data, and then write the results to. Subprograms. When a program is Fortran 77 also has some intrinsic The obvious way to solve the problem is to write a loop that runs over all the months. Note - Use the TOPEN() routines to read from tape devices. See the Fortran Library Reference Manual. Fortran Intrinsic Functions Fortran provides many commonly used functions, called intrinsic functions. To use a Fortran function.
Punched cards were used for input and output on the IBM Three passes were required to translate source code to the "IT" language, then to compile the IT statements into SOAP assembly language, and finally to produce the object program, which could then article source loaded into the machine to run the program using punched cards for data input, and outputting results onto punched cards.
Two versions existed for the s with a word memory drum: These preprocessors would typically support structured programmingvariable names longer than six characters, additional data types, conditional compilationand even macro capabilities. Despite advances in the Fortran language, preprocessors continue to be used for conditional compilation and macro substitution.