mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-22 13:00:06 +00:00
123 lines
3.2 KiB
C
123 lines
3.2 KiB
C
/* Complex tangent function for double.
|
|
Copyright (C) 1997-2012 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2.1 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
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library; if not, see
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
#include <complex.h>
|
|
#include <fenv.h>
|
|
#include <math.h>
|
|
#include <math_private.h>
|
|
#include <float.h>
|
|
|
|
__complex__ double
|
|
__ctan (__complex__ double x)
|
|
{
|
|
__complex__ double res;
|
|
|
|
if (__builtin_expect (!isfinite (__real__ x) || !isfinite (__imag__ x), 0))
|
|
{
|
|
if (__isinf_ns (__imag__ x))
|
|
{
|
|
__real__ res = __copysign (0.0, __real__ x);
|
|
__imag__ res = __copysign (1.0, __imag__ x);
|
|
}
|
|
else if (__real__ x == 0.0)
|
|
{
|
|
res = x;
|
|
}
|
|
else
|
|
{
|
|
__real__ res = __nan ("");
|
|
__imag__ res = __nan ("");
|
|
|
|
if (__isinf_ns (__real__ x))
|
|
feraiseexcept (FE_INVALID);
|
|
}
|
|
}
|
|
else
|
|
{
|
|
double sinrx, cosrx;
|
|
double den;
|
|
const int t = (int) ((DBL_MAX_EXP - 1) * M_LN2 / 2);
|
|
int rcls = fpclassify (__real__ x);
|
|
|
|
/* tan(x+iy) = (sin(2x) + i*sinh(2y))/(cos(2x) + cosh(2y))
|
|
= (sin(x)*cos(x) + i*sinh(y)*cosh(y)/(cos(x)^2 + sinh(y)^2). */
|
|
|
|
if (__builtin_expect (rcls != FP_SUBNORMAL, 1))
|
|
{
|
|
__sincos (__real__ x, &sinrx, &cosrx);
|
|
}
|
|
else
|
|
{
|
|
sinrx = __real__ x;
|
|
cosrx = 1.0;
|
|
}
|
|
|
|
if (fabs (__imag__ x) > t)
|
|
{
|
|
/* Avoid intermediate overflow when the real part of the
|
|
result may be subnormal. Ignoring negligible terms, the
|
|
imaginary part is +/- 1, the real part is
|
|
sin(x)*cos(x)/sinh(y)^2 = 4*sin(x)*cos(x)/exp(2y). */
|
|
double exp_2t = __ieee754_exp (2 * t);
|
|
|
|
__imag__ res = __copysign (1.0, __imag__ x);
|
|
__real__ res = 4 * sinrx * cosrx;
|
|
__imag__ x = fabs (__imag__ x);
|
|
__imag__ x -= t;
|
|
__real__ res /= exp_2t;
|
|
if (__imag__ x > t)
|
|
{
|
|
/* Underflow (original imaginary part of x has absolute
|
|
value > 2t). */
|
|
__real__ res /= exp_2t;
|
|
}
|
|
else
|
|
__real__ res /= __ieee754_exp (2 * __imag__ x);
|
|
}
|
|
else
|
|
{
|
|
double sinhix, coshix;
|
|
if (fabs (__imag__ x) > DBL_MIN)
|
|
{
|
|
sinhix = __ieee754_sinh (__imag__ x);
|
|
coshix = __ieee754_cosh (__imag__ x);
|
|
}
|
|
else
|
|
{
|
|
sinhix = __imag__ x;
|
|
coshix = 1.0;
|
|
}
|
|
|
|
if (fabs (sinhix) > fabs (cosrx) * DBL_EPSILON)
|
|
den = cosrx * cosrx + sinhix * sinhix;
|
|
else
|
|
den = cosrx * cosrx;
|
|
__real__ res = sinrx * cosrx / den;
|
|
__imag__ res = sinhix * coshix / den;
|
|
}
|
|
}
|
|
|
|
return res;
|
|
}
|
|
weak_alias (__ctan, ctan)
|
|
#ifdef NO_LONG_DOUBLE
|
|
strong_alias (__ctan, __ctanl)
|
|
weak_alias (__ctan, ctanl)
|
|
#endif
|