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Diffstat (limited to 'REORG.TODO/sysdeps/ieee754/ldbl-128/gamma_productl.c')
-rw-r--r-- | REORG.TODO/sysdeps/ieee754/ldbl-128/gamma_productl.c | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/REORG.TODO/sysdeps/ieee754/ldbl-128/gamma_productl.c b/REORG.TODO/sysdeps/ieee754/ldbl-128/gamma_productl.c new file mode 100644 index 0000000000..319a45119e --- /dev/null +++ b/REORG.TODO/sysdeps/ieee754/ldbl-128/gamma_productl.c @@ -0,0 +1,45 @@ +/* Compute a product of X, X+1, ..., with an error estimate. + Copyright (C) 2013-2017 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 <math.h> +#include <math_private.h> +#include <mul_splitl.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 +__gamma_productl (_Float128 x, _Float128 x_eps, int n, _Float128 *eps) +{ + SET_RESTORE_ROUNDL (FE_TONEAREST); + _Float128 ret = x; + *eps = x_eps / x; + for (int i = 1; i < n; i++) + { + *eps += x_eps / (x + i); + _Float128 lo; + mul_splitl (&ret, &lo, ret, x + i); + *eps += lo / ret; + } + return ret; +} |