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CORDIC (for COordinate Rotation DIgital Computer) is a simple and efficient algorithm to calculate hyperbolic and trigonometric functions. It is the algorithm of choice if no hardware multiplier is available, e.g. simple microcontrollers. CORDIC was first described in 1959 by Jack E. Volder.
Originally, CORDIC was implemented in binary. To oversimplify
somewhat, one begins by selecting a start angle from a small
lookup table. Then one can rotate the vector using half-angle
and sum identities. In the 1970s, decimal CORDIC became
widely used in pocket calculators, most of which operate not
in binary but in binary-coded-decimal (BCD). CORDIC is
particularly well-suited for handheld calculators, an
application for which cost (and therefore gate count on
the chip) is much more important than is speed. Also, for
scientific calculators, CORDIC routines for trigonometric
functions and hyperbolic functions can share most of their
code.
References
- Jack E. Volder, The CORDIC Trigonometric Computing Technique, IRE Transactions on Electronic Computers, September 1959
- M. E. Frerking , Digital Signal Processing in Communication Systems
- Schmid, Hermann, Decimal computation. New York, Wiley, 1974
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