72 lines
1.8 KiB
C
72 lines
1.8 KiB
C
/* Copyright (C) 1991, 1992, 1994 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Library General Public License as
|
|
published by the Free Software Foundation; either version 2 of the
|
|
License, or (at your option) any later version.
|
|
|
|
The GNU C Library is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Library General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Library General Public
|
|
License along with the GNU C Library; see the file COPYING.LIB. If
|
|
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
|
|
Cambridge, MA 02139, USA. */
|
|
|
|
#include <ansidecl.h>
|
|
#include <math.h>
|
|
|
|
#ifdef __GNUC__
|
|
|
|
double
|
|
DEFUN(atan2, (y, x), double y AND double x)
|
|
{
|
|
static CONST double one = 1.0, zero = 0.0;
|
|
double signx, signy;
|
|
double pi, PIo4, PIo2;
|
|
|
|
if (__isnan(x))
|
|
return x;
|
|
if (__isnan(y))
|
|
return y;
|
|
|
|
signy = __copysign(one, y);
|
|
signx = __copysign(one, x);
|
|
|
|
asm("fmovecr%.x %1, %0" : "=f" (pi) : "i" (0));
|
|
PIo2 = pi / 2;
|
|
PIo4 = pi / 4;
|
|
|
|
if (y == zero)
|
|
return signx == one ? y : __copysign(pi, signy);
|
|
|
|
if (x == zero)
|
|
return __copysign(PIo2, signy);
|
|
|
|
if (__isinf(x))
|
|
{
|
|
if (__isinf(y))
|
|
return __copysign(signx == one ? PIo4 : 3 * PIo4, signy);
|
|
else
|
|
return __copysign(signx == one ? zero : pi, signy);
|
|
}
|
|
|
|
if (__isinf(y))
|
|
return __copysign(PIo2, signy);
|
|
|
|
y = fabs(y);
|
|
|
|
if (x < 0.0)
|
|
/* X is negative. */
|
|
return __copysign(pi - atan(y / -x), signy);
|
|
|
|
return __copysign(atan(y / x), signy);
|
|
}
|
|
|
|
#else
|
|
#include <sysdeps/generic/atan2.c>
|
|
#endif
|