| /* Complex hyperbolic tangent for float types. |
| Copyright (C) 1997-2018 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 "quadmath-imp.h" |
| |
| __complex128 |
| ctanhq (__complex128 x) |
| { |
| __complex128 res; |
| |
| if (__glibc_unlikely (!finiteq (__real__ x) || !finiteq (__imag__ x))) |
| { |
| if (isinfq (__real__ x)) |
| { |
| __real__ res = copysignq (1, __real__ x); |
| if (finiteq (__imag__ x) && fabsq (__imag__ x) > 1) |
| { |
| __float128 sinix, cosix; |
| sincosq (__imag__ x, &sinix, &cosix); |
| __imag__ res = copysignq (0, sinix * cosix); |
| } |
| else |
| __imag__ res = copysignq (0, __imag__ x); |
| } |
| else if (__imag__ x == 0) |
| { |
| res = x; |
| } |
| else |
| { |
| if (__real__ x == 0) |
| __real__ res = __real__ x; |
| else |
| __real__ res = nanq (""); |
| __imag__ res = nanq (""); |
| |
| if (isinfq (__imag__ x)) |
| feraiseexcept (FE_INVALID); |
| } |
| } |
| else |
| { |
| __float128 sinix, cosix; |
| __float128 den; |
| const int t = (int) ((FLT128_MAX_EXP - 1) * M_LN2q / 2); |
| |
| /* tanh(x+iy) = (sinh(2x) + i*sin(2y))/(cosh(2x) + cos(2y)) |
| = (sinh(x)*cosh(x) + i*sin(y)*cos(y))/(sinh(x)^2 + cos(y)^2). */ |
| |
| if (__glibc_likely (fabsq (__imag__ x) > FLT128_MIN)) |
| { |
| sincosq (__imag__ x, &sinix, &cosix); |
| } |
| else |
| { |
| sinix = __imag__ x; |
| cosix = 1; |
| } |
| |
| if (fabsq (__real__ x) > t) |
| { |
| /* Avoid intermediate overflow when the imaginary part of |
| the result may be subnormal. Ignoring negligible terms, |
| the real part is +/- 1, the imaginary part is |
| sin(y)*cos(y)/sinh(x)^2 = 4*sin(y)*cos(y)/exp(2x). */ |
| __float128 exp_2t = expq (2 * t); |
| |
| __real__ res = copysignq (1, __real__ x); |
| __imag__ res = 4 * sinix * cosix; |
| __real__ x = fabsq (__real__ x); |
| __real__ x -= t; |
| __imag__ res /= exp_2t; |
| if (__real__ x > t) |
| { |
| /* Underflow (original real part of x has absolute value |
| > 2t). */ |
| __imag__ res /= exp_2t; |
| } |
| else |
| __imag__ res /= expq (2 * __real__ x); |
| } |
| else |
| { |
| __float128 sinhrx, coshrx; |
| if (fabsq (__real__ x) > FLT128_MIN) |
| { |
| sinhrx = sinhq (__real__ x); |
| coshrx = coshq (__real__ x); |
| } |
| else |
| { |
| sinhrx = __real__ x; |
| coshrx = 1; |
| } |
| |
| if (fabsq (sinhrx) > fabsq (cosix) * FLT128_EPSILON) |
| den = sinhrx * sinhrx + cosix * cosix; |
| else |
| den = cosix * cosix; |
| __real__ res = sinhrx * coshrx / den; |
| __imag__ res = sinix * cosix / den; |
| } |
| math_check_force_underflow_complex (res); |
| } |
| |
| return res; |
| } |