| |
| /* @(#)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 |
| <<atan2>>, <<atan2f>>---arc tangent of y/x |
| |
| INDEX |
| atan2 |
| INDEX |
| atan2f |
| |
| ANSI_SYNOPSIS |
| #include <math.h> |
| double atan2(double <[y]>,double <[x]>); |
| float atan2f(float <[y]>,float <[x]>); |
| |
| TRAD_SYNOPSIS |
| #include <math.h> |
| double atan2(<[y]>,<[x]>); |
| double <[y]>; |
| double <[x]>; |
| |
| float atan2f(<[y]>,<[x]>); |
| float <[y]>; |
| float <[x]>; |
| |
| DESCRIPTION |
| |
| <<atan2>> computes the inverse tangent (arc tangent) of <[y]>/<[x]>. |
| <<atan2>> 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). |
| |
| <<atan2f>> is identical to <<atan2>>, save that it takes and returns |
| <<float>>. |
| |
| RETURNS |
| <<atan2>> and <<atan2f>> 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, <<atan2>> causes a <<DOMAIN>> error. |
| |
| You can modify error handling for these functions using <<matherr>>. |
| |
| PORTABILITY |
| <<atan2>> is ANSI C. <<atan2f>> is an extension. |
| |
| |
| */ |
| |
| /* |
| * wrapper atan2(y,x) |
| */ |
| |
| #include "fdlibm.h" |
| #include <errno.h> |
| |
| #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) */ |
