CORDIC

CORDIC (for COordinate Rotation DIgital Computer), also known as Volder's algorithm, is a simple and efficient algorithm to calculate hyperbolic and trigonometric functions, typically converging with one digit (or bit) per iteration. It is therefore also a prominent example of digit-by-digit algorithms. CORDIC and closely related methods known as pseudo-multiplication and pseudo-division or factor combining are commonly used when no hardware multiplier is available (e.g. in simple microcontrollers and FPGAs), as the only operations it requires are addition, subtraction, bitshift and table lookup. As such, they belong to the class of shift-and-add algorithms.

Similar mathematical techniques were published by Henry Briggs as early as 1624 or Robert Flower in 1771, but CORDIC is optimized for low-complexity finite-state CPUs.

CORDIC was conceived in 1956 by Jack E. Volder at the aeroelectronics department of Convair out of necessity to replace the analog resolver in the B-58 bomber's navigation computer by a more accurate and performant real-time digital solution. Therefore, CORDIC is sometimes referred to as digital resolver.

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