CORDIC-based four quadrant inverse tangent
theta = cordicatan2(y,x)
theta = cordicatan2(y,x,niters)
theta = cordicatan2(y,x) computes the four
quadrant arctangent of
a CORDIC algorithm approximation.
theta = cordicatan2(y,x,niters) performs
of the algorithm.
Floating-point CORDIC arctangent calculation.
theta_cdat2_float = cordicatan2(0.5,-0.5) theta_cdat2_float = 2.3562
Fixed- point CORDIC arctangent calculation.
theta_cdat2_fixpt = cordicatan2(fi(0.5,1,16,15),fi(-0.5,1,16,15)); theta_cdat2_fixpt = 2.3562 DataTypeMode: Fixed-point: binary point scaling Signedness: Signed WordLength: 16 FractionLength: 13
CORDIC is an acronym for COordinate Rotation DIgital Computer. The Givens rotation-based CORDIC algorithm is one of the most hardware-efficient algorithms available because it requires only iterative shift-add operations (see References). The CORDIC algorithm eliminates the need for explicit multipliers. Using CORDIC, you can calculate various functions, such as sine, cosine, arc sine, arc cosine, arc tangent, and vector magnitude. You can also use this algorithm for divide, square root, hyperbolic, and logarithmic functions.
Increasing the number of CORDIC iterations can produce more accurate results, but doing so also increases the expense of the computation and adds latency.
The accuracy of the CORDIC kernel depends on the choice of initial values for X, Y, and Z. This algorithm uses the following initial values:
CORDIC functions discard any local
to the input.
The CORDIC functions use their own internal
The output has no attached
 Volder, JE. “The CORDIC Trigonometric Computing Technique.” IRE Transactions on Electronic Computers. Vol. EC-8, September 1959, pp. 330–334.
 Andraka, R. “A survey of CORDIC algorithm for FPGA based computers.” Proceedings of the 1998 ACM/SIGDA sixth international symposium on Field programmable gate arrays. Feb. 22–24, 1998, pp. 191–200.
 Walther, J.S. “A Unified Algorithm for Elementary Functions.” Hewlett-Packard Company, Palo Alto. Spring Joint Computer Conference, 1971, pp. 379–386. (from the collection of the Computer History Museum). www.computer.org/csdl/proceedings/afips/1971/5077/00/50770379.pdf
 Schelin, Charles W. “Calculator Function Approximation.” The American Mathematical Monthly. Vol. 90, No. 5, May 1983, pp. 317–325.
Usage notes and limitations:
Variable-size signals are not supported.
The number of iterations the CORDIC algorithm performs,
must be a constant.