|
Simula
Simula is the name of two simulation programming languages, Simula I and Simula 67, developed in the 1960s at the Norwegian Computing Center in Oslo, by Ole-Johan Dahl and Kristen Nygaard. Syntactically, it is an approximate superset of ALGOL 60, and was also influenced by the design of Simscript. Simula 67 introduced objects, classes, inheritance and subclasses, virtual procedures, coroutines, and discrete event simulation, and featured garbage collection. Other forms of subtyping (besides inheriting subclasses) were introduced in Simula derivatives. Simula is considered the first object-oriented programming language. As its name suggests, the first Simula version by 1962 was designed for doing simulations; Simula 67 though was designed to be a general-purpose programming language and provided the framework for many of the features of object-oriented languages today. Simula has been used in a wide range of applications such as simulating very-large-scale integration (VLS ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Discrete Event Simulation
A discrete-event simulation (DES) models the operation of a system as a (discrete) sequence of events in time. Each event occurs at a particular instant in time and marks a change of state in the system. Between consecutive events, no change in the system is assumed to occur; thus the simulation time can directly jump to the occurrence time of the next event, which is called next-event time progression. In addition to next-event time progression, there is also an alternative approach, called incremental time progression, where time is broken up into small time slices and the system state is updated according to the set of events/activities happening in the time slice. Because not every time slice has to be simulated, a next-event time simulation can typically run faster than a corresponding incremental time simulation. Both forms of DES contrast with continuous simulation in which the system state is changed continuously over time on the basis of a set of differential equations def ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kristen Nygaard
Kristen Nygaard (27 August 1926 – 10 August 2002) was a Norwegian computer scientist, programming language pioneer, and politician. Internationally, Nygaard is acknowledged as the co-inventor of object-oriented programming and the programming language Simula with Ole-Johan Dahl in the 1960s. Nygaard and Dahl received the 2001 A. M. Turing Award for their contribution to computer science. Early life and career Nygaard was born in Oslo and received his master's degree in mathematics at the University of Oslo in 1956. His thesis on abstract probability theory was entitled "Theoretical Aspects of Monte Carlo methods". Nygaard worked full-time at the Norwegian Defense Research Establishment from 1948 to 1960, in computing and programming (1948–1954) and operational research (1952–1960). From 1957 to 1960, he was head of the first operations research groups in the Norwegian defense establishment. He was cofounder and first chairman of the Norwegian Operational Research Societ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ole-Johan Dahl
Ole-Johan Dahl (12 October 1931 – 29 June 2002) was a Norwegian computer scientist. Dahl was a professor of computer science at the University of Oslo and is considered to be one of the fathers of Simula and object-oriented programming along with Kristen Nygaard. Career Dahl was born in Mandal, Norway. He was the son of Finn Dahl (1898–1962) and Ingrid Othilie Kathinka Pedersen (1905–80). When he was seven, his family moved to Drammen. When he was thirteen, the whole family fled to Sweden during the German occupation of Norway in World War II. After the war's end, Dahl studied numerical mathematics at the University of Oslo. Dahl became a full professor at the University of Oslo in 1968 and was a gifted teacher as well as researcher. Here he worked on ''Hierarchical Program Structures'', probably his most influential publication, which appeared co-authored with C.A.R. Hoare in the influential book ''Structured Programming'' of 1972 by Dahl, Edsger Dijkstra, and Hoare, p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Object-oriented Programming
Object-oriented programming (OOP) is a programming paradigm based on the concept of "objects", which can contain data and code. The data is in the form of fields (often known as attributes or ''properties''), and the code is in the form of procedures (often known as ''methods''). A common feature of objects is that procedures (or methods) are attached to them and can access and modify the object's data fields. In this brand of OOP, there is usually a special name such as or used to refer to the current object. In OOP, computer programs are designed by making them out of objects that interact with one another. OOP languages are diverse, but the most popular ones are class-based, meaning that objects are instances of classes, which also determine their types. Many of the most widely used programming languages (such as C++, Java, Python, etc.) are multi-paradigm and they support object-oriented programming to a greater or lesser degree, typically in combination with imper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Simulia (company)
Dassault Systèmes Simulia Corp. is a computer-aided engineering (CAE) vendor. Formerly known as Abaqus Inc. and previously Hibbitt, Karlsson & Sorensen, Inc., (HKS), the company was founded in 1978 by David Hibbitt, Bengt Karlsson and Paul Sorensen, and has its headquarters in Providence, Rhode Island. In October 2005, Dassault Systèmes acquired Abaqus, Inc. and announced Simulia, the brand encompassing all DS simulation solutions, including Abaqus and Catia Analysis applications. Dassault Systèmes Simulia Corp. is the legal entity that encompasses the Simulia brand of Dassault Systèmes. Abaqus product suite The Abaqus suite consists of three core products - Abaqus/Standard, Abaqus/Explicit and Abaqus/CAE (Complete Abaqus Environment). In addition to this, recent versions of Abaqus (6.10 onwards) also contain Abaqus/CFD for computational fluid dynamic simulations. Each of these packages offers additional, optional modules that address specialized capabilities required by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Simscript
SIMSCRIPT is a free-form, English-like general-purpose simulation language conceived by Harry Markowitz and Bernard Hausner at the RAND Corporation in 1962. It was implemented as a Fortran preprocessor on the IBM 7090 and was designed for large discrete event simulations. It influenced Simula. Though earlier versions were released into the public domain, SIMSCRIPT was commercialized by Markowitz's company, California Analysis Center, Inc. (CACI), which produced proprietary versions SIMSCRIPT I.5 and SIMSCRIPT II.5. SIMSCRIPT II.5 SIMSCRIPT II.5 was the last pre-PC incarnation of SIMSCRIPT, one of the oldest computer simulation languages. Although military contractor CACI released it in 1971, it still enjoys wide use in large-scale military and air-traffic control simulations. :''SIMSCRIPT II.5 is a powerful, free-form, English-like, general-purpose simulation programming language. It supports the application of software engineering principles, such as structured programming and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ALGOL
ALGOL (; short for "Algorithmic Language") is a family of imperative computer programming languages originally developed in 1958. ALGOL heavily influenced many other languages and was the standard method for algorithm description used by the Association for Computing Machinery (ACM) in textbooks and academic sources for more than thirty years. In the sense that the syntax of most modern languages is "Algol-like", it was arguably more influential than three other high-level programming languages among which it was roughly contemporary: FORTRAN, Lisp, and COBOL. It was designed to avoid some of the perceived problems with FORTRAN and eventually gave rise to many other programming languages, including PL/I, Simula, BCPL, B, Pascal, and C. ALGOL introduced code blocks and the begin...end pairs for delimiting them. It was also the first language implementing nested function definitions with lexical scope. Moreover, it was the first programming language which gave detail ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ALGOL 60
ALGOL 60 (short for ''Algorithmic Language 1960'') is a member of the ALGOL family of computer programming languages. It followed on from ALGOL 58 which had introduced code blocks and the begin and end pairs for delimiting them, representing a key advance in the rise of structured programming. ALGOL 60 was the first language implementing nested function definitions with lexical scope. It gave rise to many other programming languages, including CPL, Simula, BCPL, B, Pascal, and C. Practically every computer of the era had a systems programming language based on ALGOL 60 concepts. Niklaus Wirth based his own ALGOL W on ALGOL 60 before moving to develop Pascal. Algol-W was intended to be the next generation ALGOL but the ALGOL 68 committee decided on a design that was more complex and advanced rather than a cleaned simplified ALGOL 60. The official ALGOL versions are named after the year they were first published. Algol 68 is substantially different from Algol 60 and was cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inheritance (object-oriented Programming)
In object-oriented programming, inheritance is the mechanism of basing an object or class upon another object ( prototype-based inheritance) or class ( class-based inheritance), retaining similar implementation. Also defined as deriving new classes ( sub classes) from existing ones such as super class or base class and then forming them into a hierarchy of classes. In most class-based object-oriented languages, an object created through inheritance, a "child object", acquires all the properties and behaviors of the "parent object" , with the exception of: constructors, destructor, overloaded operators and friend functions of the base class. Inheritance allows programmers to create classes that are built upon existing classes, to specify a new implementation while maintaining the same behaviors ( realizing an interface), to reuse code and to independently extend original software via public classes and interfaces. The relationships of objects or classes through inheritance give ris ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TOPS-10
TOPS-10 System (''Timesharing / Total Operating System-10'') is a discontinued operating system from Digital Equipment Corporation (DEC) for the PDP-10 (or DECsystem-10) mainframe computer family. Launched in 1967, TOPS-10 evolved from the earlier "Monitor" software for the PDP-6 and PDP-10 computers; this was renamed to TOPS-10 in 1970. Overview TOPS-10 supported shared memory and allowed the development of one of the first true multiplayer computer games. The game, called DECWAR, was a text-oriented ''Star Trek'' type game. Users at terminals typed in commands and fought each other in real time. TOPS-10 was also the home of the original Multi User Dungeon, MUD, the fore runner to today's MMORPGs. Another groundbreaking application was called ''FORUM''. This application was perhaps the first so-called ''CB Simulator'' that allowed users to converse with one another in what is now known as a chat room. This application showed the potential of multi-user communication and led ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subclass (computer Science)
In object-oriented programming, inheritance is the mechanism of basing an object or class upon another object ( prototype-based inheritance) or class ( class-based inheritance), retaining similar implementation. Also defined as deriving new classes ( sub classes) from existing ones such as super class or base class and then forming them into a hierarchy of classes. In most class-based object-oriented languages, an object created through inheritance, a "child object", acquires all the properties and behaviors of the "parent object" , with the exception of: constructors, destructor, overloaded operators and friend functions of the base class. Inheritance allows programmers to create classes that are built upon existing classes, to specify a new implementation while maintaining the same behaviors ( realizing an interface), to reuse code and to independently extend original software via public classes and interfaces. The relationships of objects or classes through inheritance give ris ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Imperative Programming
In computer science, imperative programming is a programming paradigm of software that uses statements that change a program's state. In much the same way that the imperative mood in natural languages expresses commands, an imperative program consists of commands for the computer to perform. Imperative programming focuses on describing ''how'' a program operates step by step, rather than on high-level descriptions of its expected results. The term is often used in contrast to declarative programming, which focuses on ''what'' the program should accomplish without specifying all the details of ''how'' the program should achieve the result. Imperative and procedural programming Procedural programming is a type of imperative programming in which the program is built from one or more procedures (also termed subroutines or functions). The terms are often used as synonyms, but the use of procedures has a dramatic effect on how imperative programs appear and how they are constructed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
