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Hash Map
In computer science, a hash table is a data structure that implements an associative array, also called a dictionary or simply map; an associative array is an abstract data type that maps Unique key, keys to Value (computer science), values. A hash table uses a hash function to compute an ''index'', also called a ''hash code'', into an array of ''buckets'' or ''slots'', from which the desired value can be found. During lookup, the key is hashed and the resulting hash indicates where the corresponding value is stored. A map implemented by a hash table is called a hash map. Most hash table designs employ an Perfect hash function, imperfect hash function. Hash collision, Hash collisions, where the hash function generates the same index for more than one key, therefore typically must be accommodated in some way. In a well-dimensioned hash table, the average time complexity for each lookup is independent of the number of elements stored in the table. Many hash table designs also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Associative Array
In computer science, an associative array, key-value store, map, symbol table, or dictionary is an abstract data type that stores a collection of (key, value) pairs, such that each possible key appears at most once in the collection. In mathematical terms, an associative array is a function with ''finite'' domain. It supports 'lookup', 'remove', and 'insert' operations. The dictionary problem is the classic problem of designing efficient data structures that implement associative arrays. The two major solutions to the dictionary problem are hash tables and search trees..Dietzfelbinger, M., Karlin, A., Mehlhorn, K., Meyer auf der Heide, F., Rohnert, H., and Tarjan, R. E. 1994"Dynamic Perfect Hashing: Upper and Lower Bounds". SIAM J. Comput. 23, 4 (Aug. 1994), 738-761. http://portal.acm.org/citation.cfm?id=182370 It is sometimes also possible to solve the problem using directly addressed arrays, binary search trees, or other more specialized structures. Many programmin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Table (computing)
In computer science, a lookup table (LUT) is an array that replaces runtime computation of a mathematical function with a simpler array indexing operation, in a process termed as ''direct addressing''. The savings in processing time can be significant, because retrieving a value from memory is often faster than carrying out an "expensive" computation or input/output operation. The tables may be precalculated and stored in static program storage, calculated (or "pre-fetched") as part of a program's initialization phase ('' memoization''), or even stored in hardware in application-specific platforms. Lookup tables are also used extensively to validate input values by matching against a list of valid (or invalid) items in an array and, in some programming languages, may include pointer functions (or offsets to labels) to process the matching input. FPGAs also make extensive use of reconfigurable, hardware-implemented, lookup tables to provide programmable hardware functionality ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Assembly Language
In computing, assembly language (alternatively assembler language or symbolic machine code), often referred to simply as assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence between the instructions in the language and the architecture's machine code instructions. Assembly language usually has one statement per machine instruction (1:1), but constants, comments, assembler directives, symbolic labels of, e.g., memory locations, registers, and macros are generally also supported. The first assembly code in which a language is used to represent machine code instructions is found in Kathleen and Andrew Donald Booth's 1947 work, ''Coding for A.R.C.''. Assembly code is converted into executable machine code by a utility program referred to as an '' assembler''. The term "assembler" is generally attributed to Wilkes, Wheeler and Gill in their 1951 book '' The Preparation of Programs for an Electronic Dig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM 701
The IBM 701 Electronic Data Processing Machine, known as the Defense Calculator while in development, was IBM’s first commercial scientific computer and its first series production mainframe computer, which was announced to the public on May 21, 1952. It was designed and developed by Jerrier Haddad and Nathaniel Rochester and was based on the IAS machine at Princeton. The IBM 701 was the first computer in the IBM 700/7000 series, which were IBM’s high-end computers until the arrival of the IBM System/360 in 1964. The business-oriented sibling of the 701 was the IBM 702 and a lower-cost general-purpose sibling was the IBM 650, which gained fame as the first mass-produced computer. History IBM 701 competed with Remington Rand's UNIVAC 1103 in the scientific computation market. In early 1954, a committee of the Joint Chiefs of Staff requested that the two machines be compared for the purpose of using them for a Joint Numerical Weather Prediction project. Based on the t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM Research
IBM Research is the research and development division for IBM, an American Multinational corporation, multinational information technology company. IBM Research is headquartered at the Thomas J. Watson Research Center in Yorktown Heights, New York, near IBM headquarters in Armonk, New York. It is the largest industrial research organization in the world with operations in over 170 countries and twelve labs on six continents. IBM employees have garnered six Nobel Prizes, six Turing Awards, 20 inductees into the U.S. National Inventors Hall of Fame, 19 National Medal of Technology, National Medals of Technology, five National Medal of Science, National Medals of Science and three Kavli Foundation (United States)#The Kavli Prize, Kavli Prizes. , the company has generated more patents than any other business in each of 25 consecutive years, which is a record. History The roots of today's IBM Research began with the 1945 opening of the Watson Scientific Computing Laboratory at Columbi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthur Samuel (computer Scientist)
Arthur Lee Samuel (December 5, 1901 – July 29, 1990) was an American pioneer in the field of computer gaming and artificial intelligence. He popularized the term "machine learning" in 1959. The Samuel Checkers-playing Program was among the world's first successful self-learning programs, and as such a very early demonstration of the fundamental concept of artificial intelligence (AI). He was also a senior member in the TeX community who devoted much time giving personal attention to the needs of users and wrote an early TeX manual in 1983. Biography Samuel was born on December 5, 1901, in Emporia, Kansas, and graduated from the College of Emporia in Kansas in 1923. He received a master's degree in Electrical Engineering from MIT in 1926, and taught for two years as an instructor. In 1928, he joined Bell Laboratories, where he worked mostly on vacuum tubes, including improvements of radar during World War II. He developed a gas-discharge transmit-receive switch (TR tube) that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nathaniel Rochester (computer Scientist)
Nathaniel Rochester (January 14, 1919 – June 8, 2001) was the chief architect of the IBM 701, the first mass produced scientific computer, and of the prototype of its first commercial version, the IBM 702. He wrote the first assembler and participated in the founding of the field of artificial intelligence. Early work Rochester received his B.S. degree in electrical engineering from the Massachusetts Institute of Technology in 1941. He stayed on at MIT in the Radiation Laboratory for three years and then moved to Sylvania Electric Products where he was responsible for the design and construction of radar sets and other military equipment. His group built the arithmetic element for the Whirlwind I computer at MIT. IBM 701 computer In 1948, Rochester moved to IBM, where he co-designed, along with Jerrier Haddad, the first mass-produced scientific computer, the IBM 701. He wrote the first symbolic assembler, which allowed programs to be written in short, readable co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elaine M
Elaine may refer to: Arts and entertainment * , opera composed by Herman Bemberg * "Elaine" (short story), 1945 short story by J. D. Salinger * "Elaine" (song), by ABBA Places * Elaine, Victoria, a town in Australia * Elaine, Arkansas, a US city People * Elaine (given name), real people and fictional characters with the given name * Elaine (legend), name shared by several different female characters in Arthurian legend, including: ** Elaine of Astolat ** Elaine of Corbenic * Elaine (singer), South African singer See also * Elaine's, a New York City restaurant * ''The Exploits of Elaine ''The Exploits of Elaine'' is a 1914 American Serial (film), film serial in the damsel in distress genre of ''The Perils of Pauline (1914 serial), The Perils of Pauline'' (1914). ''The Exploits of Elaine'' tells the story of a young woman named ...'', 1914 film serial in the genre of ''The Perils of Pauline'' * "Miss Elaine", song by Run–D.M.C. from the album '' Tougher Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene Amdahl
Gene Myron Amdahl (November 16, 1922 – November 10, 2015) was an American computer architect and high-tech entrepreneur, chiefly known for his work on mainframe computers at IBM and later his own companies, especially Amdahl Corporation. He formulated Amdahl's law, which states a fundamental limitation of parallel computing. Childhood and education Amdahl was born to immigrant parents of Norwegian and Swedish descent in Flandreau, South Dakota. After serving in the Navy during World War II he completed a degree in engineering physics at South Dakota State University in 1948. He went on to study theoretical physics at the University of Wisconsin–Madison under Robert G. Sachs. However, in 1950, Amdahl and Charles H. "Charlie" Davidson, a fellow PhD student in the Department of Physics, approached Prof. Harold A. Peterson with the idea of a digital computer. Amdahl and Davidson gained the support of Peterson and fellow electrical engineering professor Vincent C. Rideo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Open Addressing
Open addressing, or closed hashing, is a method of Hash table#Collision resolution, collision resolution in hash tables. With this method a hash collision is resolved by probing, or searching through alternative locations in the array (the ''probe sequence'') until either the target record is found, or an unused array slot is found, which indicates that there is no such key in the table. Well-known probe sequences include: ; Linear probing : in which the interval between probes is fixed — often set to 1. ; Quadratic probing : in which the interval between probes increases linearly (hence, the indices are described by a quadratic function). ; Double hashing : in which the interval between probes is fixed for each record but is computed by another hash function. The main trade offs between these methods are that linear probing has the best Locality of reference, cache performance but is most sensitive to Primary clustering, clustering, while double hashing has poor cache perf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hans Peter Luhn
Hans Peter Luhn (July 1, 1896 – August 19, 1964) was a German-American researcher in the field of computer science and Library & Information Science for IBM, and creator of the Luhn algorithm, KWIC (Key Words In Context) indexing, and selective dissemination of information ("SDI"). His inventions have found applications in diverse areas like computer science, the textile industry, linguistics, and information science. He was awarded over 80 patents. He created one of the earliest practical hash functions in the 1950s. Early life and education Luhn was born in Barmen, Germany (now part of Wuppertal) on July 1, 1896. After he completed secondary school, Luhn moved to Switzerland to learn the printing trade so he could join the family business. His career in printing was halted by his service as a communications officer in the German Army during World War I. Career After the war, Luhn entered the textile field, which eventually led him to the United States, where he inv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Set (abstract Data Type)
In computer science, a set is an abstract data type that can store unique values, without any particular sequence, order. It is a computer implementation of the mathematics, mathematical concept of a finite set. Unlike most other collection (abstract data type), collection types, rather than retrieving a specific element from a set, one typically tests a value for membership in a set. Some set data structures are designed for static or frozen sets that do not change after they are constructed. Static sets allow only query operations on their elements — such as checking whether a given value is in the set, or enumerating the values in some arbitrary order. Other variants, called dynamic or mutable sets, allow also the insertion and deletion of elements from the set. A multiset is a special kind of set in which an element can appear multiple times in the set. Type theory In type theory, sets are generally identified with their indicator function (characteristic function): accord ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
