A general technique of error reduction to improve the accuracy of four-quadrant arctangent approximations through the Möbius transformation is proposed. Simple identities connecting the regular arctangent function and the four-quadrant arctangent function are derived and used to obtain novel four-quadrant arctangent approximations. The new approximations can provide improved accuracy at the expense of a moderate increase in computational cost.

IET Signal Processing
Department of Systems and Computer Engineering

Rajan, S, Wang, S. (S.), & Inkol, R. (R.). (2008). Error reduction technique for four-quadrant arctangent approximations. In IET Signal Processing (Vol. 2, pp. 133–138). doi:10.1049/iet-spr:20070117