## Mercurial > hg > CbC > CbC_gcc

### view libquadmath/math/tgammaq_product.c @ 158:494b0b89df80 default tip

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author | Shinji KONO <kono@ie.u-ryukyu.ac.jp> |
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date | Mon, 25 May 2020 18:13:55 +0900 |

parents | 1830386684a0 |

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/* Compute a product of X, X+1, ..., with an error estimate. Copyright (C) 2013-2018 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 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" /* Compute the product of X + X_EPS, X + X_EPS + 1, ..., X + X_EPS + N - 1, in the form R * (1 + *EPS) where the return value R is an approximation to the product and *EPS is set to indicate the approximate error in the return value. X is such that all the values X + 1, ..., X + N - 1 are exactly representable, and X_EPS / X is small enough that factors quadratic in it can be neglected. */ __float128 __quadmath_gamma_productq (__float128 x, __float128 x_eps, int n, __float128 *eps) { SET_RESTORE_ROUNDF128 (FE_TONEAREST); __float128 ret = x; *eps = x_eps / x; for (int i = 1; i < n; i++) { *eps += x_eps / (x + i); __float128 lo; mul_splitq (&ret, &lo, ret, x + i); *eps += lo / ret; } return ret; }