/* Complex tangent function for long double.
- Copyright (C) 1997, 2005, 2011 Free Software Foundation, Inc.
+ Copyright (C) 1997-2014 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
#include <complex.h>
#include <fenv.h>
#include <math.h>
-
#include <math_private.h>
-
+#include <float.h>
__complex__ long double
__ctanl (__complex__ long double x)
{
__complex__ long double res;
- if (__builtin_expect (!isfinite (__real__ x) || !isfinite (__imag__ x), 0))
+ if (__glibc_unlikely (!isfinite (__real__ x) || !isfinite (__imag__ x)))
{
if (__isinf_nsl (__imag__ x))
{
}
else
{
- long double sin2rx, cos2rx;
+ long double sinrx, cosrx;
long double den;
+ const int t = (int) ((LDBL_MAX_EXP - 1) * M_LN2l / 2);
+ int rcls = fpclassify (__real__ x);
- __sincosl (2.0 * __real__ x, &sin2rx, &cos2rx);
-
- den = cos2rx + __ieee754_coshl (2.0 * __imag__ 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 (__glibc_likely (rcls != FP_SUBNORMAL))
+ {
+ __sincosl (__real__ x, &sinrx, &cosrx);
+ }
+ else
+ {
+ sinrx = __real__ x;
+ cosrx = 1.0;
+ }
- if (den == 0.0)
+ if (fabsl (__imag__ x) > t)
{
- __complex__ long double ez = __cexpl (1.0i * x);
- __complex__ long double emz = __cexpl (-1.0i * x);
+ /* 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). */
+ long double exp_2t = __ieee754_expl (2 * t);
- res = (ez - emz) / (ez + emz) * -1.0i;
+ __imag__ res = __copysignl (1.0, __imag__ x);
+ __real__ res = 4 * sinrx * cosrx;
+ __imag__ x = fabsl (__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_expl (2 * __imag__ x);
}
else
{
- __real__ res = sin2rx / den;
- __imag__ res = __ieee754_sinhl (2.0 * __imag__ x) / den;
+ long double sinhix, coshix;
+ if (fabsl (__imag__ x) > LDBL_MIN)
+ {
+ sinhix = __ieee754_sinhl (__imag__ x);
+ coshix = __ieee754_coshl (__imag__ x);
+ }
+ else
+ {
+ sinhix = __imag__ x;
+ coshix = 1.0L;
+ }
+
+ if (fabsl (sinhix) > fabsl (cosrx) * LDBL_EPSILON)
+ den = cosrx * cosrx + sinhix * sinhix;
+ else
+ den = cosrx * cosrx;
+ __real__ res = sinrx * cosrx / den;
+ __imag__ res = sinhix * coshix / den;
}
}