/* @(#)w_atan2.c 5.1 93/09/24 */ /* * ==================================================== * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. * * Developed at SunPro, a Sun Microsystems, Inc. business. * Permission to use, copy, modify, and distribute this * software is freely granted, provided that this notice * is preserved. * ==================================================== * */ /* FUNCTION <>, <>---arc tangent of y/x INDEX atan2 INDEX atan2f ANSI_SYNOPSIS #include double atan2(double <[y]>,double <[x]>); float atan2f(float <[y]>,float <[x]>); TRAD_SYNOPSIS #include double atan2(<[y]>,<[x]>); double <[y]>; double <[x]>; float atan2f(<[y]>,<[x]>); float <[y]>; float <[x]>; DESCRIPTION <> computes the inverse tangent (arc tangent) of <[y]>/<[x]>. <> produces the correct result even for angles near @ifinfo pi/2 or -pi/2 @end ifinfo @tex $\pi/2$ or $-\pi/2$ @end tex (that is, when <[x]> is near 0). <> is identical to <>, save that it takes and returns <>. RETURNS <> and <> return a value in radians, in the range of @ifinfo -pi to pi. @end ifinfo @tex $-\pi$ to $\pi$. @end tex If both <[x]> and <[y]> are 0.0, <> causes a <> error. You can modify error handling for these functions using <>. PORTABILITY <> is ANSI C. <> is an extension. */ /* * wrapper atan2(y,x) */ #include "fdlibm.h" #include #ifndef _DOUBLE_IS_32BITS #ifdef __STDC__ double atan2(double y, double x) /* wrapper atan2 */ #else double atan2(y,x) /* wrapper atan2 */ double y,x; #endif { #ifdef _IEEE_LIBM return __ieee754_atan2(y,x); #else double z; struct exception exc; z = __ieee754_atan2(y,x); if(_LIB_VERSION == _IEEE_||isnan(x)||isnan(y)) return z; if(x==0.0&&y==0.0) { /* atan2(+-0,+-0) */ exc.arg1 = y; exc.arg2 = x; exc.type = DOMAIN; exc.name = "atan2"; exc.err = 0; exc.retval = 0.0; if(_LIB_VERSION == _POSIX_) errno = EDOM; else if (!matherr(&exc)) { errno = EDOM; } if (exc.err != 0) errno = exc.err; return exc.retval; } else return z; #endif } #endif /* defined(_DOUBLE_IS_32BITS) */