Patent ID: 6470367
Filing Date: 2002-10-22
Classification: G06F

Abstract:
An apparatus for implementing an inverse arctangent function using piecewise linear theorem to simplify, used to transform a right-angled coordinate point X and Y to a phase angle &thgr; of an inverse arctangent function, comprising:a processing unit, used to transform a right-angled coordinate point X and Y to a phase angle &thgr; of an inverse arctangent function; said processing unit employing the following equation to operate: Î¸^=Î©&it;(s)+Î¦&it;(s)&CenterDot;(c&it;(k)+d&it;(k)&CenterDot;ymxm)wherein {circumflex over (&thgr;)} represents the approximate value of the phase angle &thgr;, ym represents the smaller absolute value of the values X and Y, xm represents the smaller absolute value of the values X and Y; c(k) and d(k) represent coefficient parameters of the equation, &OHgr;(s), &PHgr;(s) are transformation parameters that are used to map the phase angle &thgr; between 45 degree to 360 degree to the approximate phase angle {circumflex over (&thgr;)} between 0 degree to 45 degree; said processing unit including: an absolute value comparing mechanism, used to generate xm and ym; a piecewise linear mechanism connected to said absolute value comparing mechanism for generating ymxm;a multiplier/adder mechanism connected to said absolute value comparing mechanism and a memory unit for generating c&it;(k)+d&it;(k)*ymxm;an eight-octant mapping mechanism connected to said multiplier/adder mechanism for generating Î¸=Î©&it;(s)+Î¦&it;(s)&it;â€ƒ&it;(c&it;(k)+d&it;(k)&CenterDot;ymxm);â€ƒand a memory unit connected to said processing unit for storing the values of c(k) and d(k).