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The first class-D amplifier was invented by British scientist Alec Reeves in the 1950s and was first called by that name in 1955. The first commercial product was a kit module called the X-10 released by Sinclair Radionics in 1964. However, it had an output power of only 2.5 watts. The Sinclair X-20 in 1966 produced 20 watts but suffered from ...
A mathematical model is an abstract description of a concrete system using mathematical concepts and language. The process of developing a mathematical model is termed mathematical modeling. Mathematical models are used in applied mathematics and in the natural sciences (such as physics, biology, earth science, chemistry) and engineering ...
000 Computer science, knowledge, and systems. 000 Computer science, information and general works. 001 Knowledge. 002 The book (writing, libraries, and book-related topics) 003 Systems. 004 Data processing and computer science. 005 Computer programming, programs, and data. 006 Special computer methods (e.g. AI, multimedia, VR) [ 4]
Mathematics Portal. v. t. e. In contemporary education, mathematics education —known in Europe as the didactics or pedagogy of mathematics —is the practice of teaching, learning, and carrying out scholarly research into the transfer of mathematical knowledge.
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List of online encyclopedias. This is a list of well-known online encyclopedias that are accessible or formerly accessible on the Internet . The largest online encyclopedias are general reference works, though there are also many specialized ones. Some online encyclopedias are editions of a print encyclopedia, such as Encyclopædia Britannica ...
Catalog or catalogue may refer to: Cataloging. in science and technology. Library catalog, a catalog of books and other media. Union catalog, a combined library catalog describing the collections of a number of libraries. Calendar (archives) and Finding aid, catalogs of an archive. Astronomical catalog, a catalog of astronomical objects.
7 is the only number D for which the equation 2 n − D = x 2 has more than two solutions for n and x natural. In particular, the equation 2 n − 7 = x 2 is known as the Ramanujan–Nagell equation. 7 is one of seven numbers in the positive definite quadratic integer matrix representative of all odd numbers: {1, 3, 5, 7, 11, 15, 33}. [19] [20]