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Fix cacosh inaccuracy and spurious exceptions (bug 15327).

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This commit is contained in:
Joseph Myers
2013-04-02 22:54:00 +00:00
parent e7906a4789
commit 52ce486045
8 changed files with 2300 additions and 130 deletions
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32
math/s_cacosh.c
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@ -64,31 +64,25 @@ __cacosh (__complex__ double x)
__real__ res = 0.0;
__imag__ res = __copysign (M_PI_2, __imag__ x);
}
/* The factor 16 is just a guess. */
else if (16.0 * fabs (__imag__ x) < fabs (__real__ x))
{
/* Kahan's formula which avoid cancellation through subtraction in
some cases. */
res = 2.0 * __clog (__csqrt ((x + 1.0) / 2.0) + __csqrt ((x - 1.0) / 2.0));
if (signbit (__real__ res))
__real__ res = 0.0;
}
else
{
__complex__ double y;
__real__ y = (__real__ x - __imag__ x) * (__real__ x + __imag__ x) - 1.0;
__imag__ y = 2.0 * __real__ x * __imag__ x;
__real__ y = -__imag__ x;
__imag__ y = __real__ x;
y = __csqrt (y);
y = __kernel_casinh (y, 1);
if (signbit (__real__ x))
y = -y;
__real__ y += __real__ x;
__imag__ y += __imag__ x;
res = __clog (y);
if (signbit (__imag__ x))
{
__real__ res = __real__ y;
__imag__ res = -__imag__ y;
}
else
{
__real__ res = -__real__ y;
__imag__ res = __imag__ y;
}
}
return res;