diff options
Diffstat (limited to 'sysdeps/ieee754/dbl-64/e_gamma_r.c')
| -rw-r--r-- | sysdeps/ieee754/dbl-64/e_gamma_r.c | 220 |
1 files changed, 0 insertions, 220 deletions
diff --git a/sysdeps/ieee754/dbl-64/e_gamma_r.c b/sysdeps/ieee754/dbl-64/e_gamma_r.c deleted file mode 100644 index 818fa94766..0000000000 --- a/sysdeps/ieee754/dbl-64/e_gamma_r.c +++ /dev/null @@ -1,220 +0,0 @@ -/* Implementation of gamma function according to ISO C. - Copyright (C) 1997-2017 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 <math.h> -#include <math_private.h> -#include <float.h> - -/* Coefficients B_2k / 2k(2k-1) of x^-(2k-1) inside exp in Stirling's - approximation to gamma function. */ - -static const double gamma_coeff[] = - { - 0x1.5555555555555p-4, - -0xb.60b60b60b60b8p-12, - 0x3.4034034034034p-12, - -0x2.7027027027028p-12, - 0x3.72a3c5631fe46p-12, - -0x7.daac36664f1f4p-12, - }; - -#define NCOEFF (sizeof (gamma_coeff) / sizeof (gamma_coeff[0])) - -/* Return gamma (X), for positive X less than 184, in the form R * - 2^(*EXP2_ADJ), where R is the return value and *EXP2_ADJ is set to - avoid overflow or underflow in intermediate calculations. */ - -static double -gamma_positive (double x, int *exp2_adj) -{ - int local_signgam; - if (x < 0.5) - { - *exp2_adj = 0; - return __ieee754_exp (__ieee754_lgamma_r (x + 1, &local_signgam)) / x; - } - else if (x <= 1.5) - { - *exp2_adj = 0; - return __ieee754_exp (__ieee754_lgamma_r (x, &local_signgam)); - } - else if (x < 6.5) - { - /* Adjust into the range for using exp (lgamma). */ - *exp2_adj = 0; - double n = __ceil (x - 1.5); - double x_adj = x - n; - double eps; - double prod = __gamma_product (x_adj, 0, n, &eps); - return (__ieee754_exp (__ieee754_lgamma_r (x_adj, &local_signgam)) - * prod * (1.0 + eps)); - } - else - { - double eps = 0; - double x_eps = 0; - double x_adj = x; - double prod = 1; - if (x < 12.0) - { - /* Adjust into the range for applying Stirling's - approximation. */ - double n = __ceil (12.0 - x); - x_adj = math_narrow_eval (x + n); - x_eps = (x - (x_adj - n)); - prod = __gamma_product (x_adj - n, x_eps, n, &eps); - } - /* The result is now gamma (X_ADJ + X_EPS) / (PROD * (1 + EPS)). - Compute gamma (X_ADJ + X_EPS) using Stirling's approximation, - starting by computing pow (X_ADJ, X_ADJ) with a power of 2 - factored out. */ - double exp_adj = -eps; - double x_adj_int = __round (x_adj); - double x_adj_frac = x_adj - x_adj_int; - int x_adj_log2; - double x_adj_mant = __frexp (x_adj, &x_adj_log2); - if (x_adj_mant < M_SQRT1_2) - { - x_adj_log2--; - x_adj_mant *= 2.0; - } - *exp2_adj = x_adj_log2 * (int) x_adj_int; - double ret = (__ieee754_pow (x_adj_mant, x_adj) - * __ieee754_exp2 (x_adj_log2 * x_adj_frac) - * __ieee754_exp (-x_adj) - * __ieee754_sqrt (2 * M_PI / x_adj) - / prod); - exp_adj += x_eps * __ieee754_log (x_adj); - double bsum = gamma_coeff[NCOEFF - 1]; - double x_adj2 = x_adj * x_adj; - for (size_t i = 1; i <= NCOEFF - 1; i++) - bsum = bsum / x_adj2 + gamma_coeff[NCOEFF - 1 - i]; - exp_adj += bsum / x_adj; - return ret + ret * __expm1 (exp_adj); - } -} - -double -__ieee754_gamma_r (double x, int *signgamp) -{ - int32_t hx; - u_int32_t lx; - double ret; - - EXTRACT_WORDS (hx, lx, x); - - if (__glibc_unlikely (((hx & 0x7fffffff) | lx) == 0)) - { - /* Return value for x == 0 is Inf with divide by zero exception. */ - *signgamp = 0; - return 1.0 / x; - } - if (__builtin_expect (hx < 0, 0) - && (u_int32_t) hx < 0xfff00000 && __rint (x) == x) - { - /* Return value for integer x < 0 is NaN with invalid exception. */ - *signgamp = 0; - return (x - x) / (x - x); - } - if (__glibc_unlikely ((unsigned int) hx == 0xfff00000 && lx == 0)) - { - /* x == -Inf. According to ISO this is NaN. */ - *signgamp = 0; - return x - x; - } - if (__glibc_unlikely ((hx & 0x7ff00000) == 0x7ff00000)) - { - /* Positive infinity (return positive infinity) or NaN (return - NaN). */ - *signgamp = 0; - return x + x; - } - - if (x >= 172.0) - { - /* Overflow. */ - *signgamp = 0; - ret = math_narrow_eval (DBL_MAX * DBL_MAX); - return ret; - } - else - { - SET_RESTORE_ROUND (FE_TONEAREST); - if (x > 0.0) - { - *signgamp = 0; - int exp2_adj; - double tret = gamma_positive (x, &exp2_adj); - ret = __scalbn (tret, exp2_adj); - } - else if (x >= -DBL_EPSILON / 4.0) - { - *signgamp = 0; - ret = 1.0 / x; - } - else - { - double tx = __trunc (x); - *signgamp = (tx == 2.0 * __trunc (tx / 2.0)) ? -1 : 1; - if (x <= -184.0) - /* Underflow. */ - ret = DBL_MIN * DBL_MIN; - else - { - double frac = tx - x; - if (frac > 0.5) - frac = 1.0 - frac; - double sinpix = (frac <= 0.25 - ? __sin (M_PI * frac) - : __cos (M_PI * (0.5 - frac))); - int exp2_adj; - double tret = M_PI / (-x * sinpix - * gamma_positive (-x, &exp2_adj)); - ret = __scalbn (tret, -exp2_adj); - math_check_force_underflow_nonneg (ret); - } - } - ret = math_narrow_eval (ret); - } - if (isinf (ret) && x != 0) - { - if (*signgamp < 0) - { - ret = math_narrow_eval (-__copysign (DBL_MAX, ret) * DBL_MAX); - ret = -ret; - } - else - ret = math_narrow_eval (__copysign (DBL_MAX, ret) * DBL_MAX); - return ret; - } - else if (ret == 0) - { - if (*signgamp < 0) - { - ret = math_narrow_eval (-__copysign (DBL_MIN, ret) * DBL_MIN); - ret = -ret; - } - else - ret = math_narrow_eval (__copysign (DBL_MIN, ret) * DBL_MIN); - return ret; - } - else - return ret; -} -strong_alias (__ieee754_gamma_r, __gamma_r_finite) |