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Diffstat (limited to 'Build/source/libs/mpfr/mpfr-3.1.2/src/tan.c')
-rw-r--r-- | Build/source/libs/mpfr/mpfr-3.1.2/src/tan.c | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/Build/source/libs/mpfr/mpfr-3.1.2/src/tan.c b/Build/source/libs/mpfr/mpfr-3.1.2/src/tan.c new file mode 100644 index 00000000000..8cd93cdeff2 --- /dev/null +++ b/Build/source/libs/mpfr/mpfr-3.1.2/src/tan.c @@ -0,0 +1,89 @@ +/* mpfr_tan -- tangent of a floating-point number + +Copyright 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Free Software Foundation, Inc. +Contributed by the AriC and Caramel projects, INRIA. + +This file is part of the GNU MPFR Library. + +The GNU MPFR 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 3 of the License, or (at your +option) any later version. + +The GNU MPFR 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 MPFR Library; see the file COPYING.LESSER. If not, see +http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc., +51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */ + +#define MPFR_NEED_LONGLONG_H +#include "mpfr-impl.h" + +/* computes tan(x) = sign(x)*sqrt(1/cos(x)^2-1) */ +int +mpfr_tan (mpfr_ptr y, mpfr_srcptr x, mpfr_rnd_t rnd_mode) +{ + mpfr_prec_t precy, m; + int inexact; + mpfr_t s, c; + MPFR_ZIV_DECL (loop); + MPFR_SAVE_EXPO_DECL (expo); + MPFR_GROUP_DECL (group); + + MPFR_LOG_FUNC + (("x[%Pu]=%.*Rg rnd=%d", mpfr_get_prec (x), mpfr_log_prec, x, rnd_mode), + ("y[%Pu]=%.*Rg inexact=%d", + mpfr_get_prec (y), mpfr_log_prec, y, inexact)); + + if (MPFR_UNLIKELY(MPFR_IS_SINGULAR(x))) + { + if (MPFR_IS_NAN(x) || MPFR_IS_INF(x)) + { + MPFR_SET_NAN(y); + MPFR_RET_NAN; + } + else /* x is zero */ + { + MPFR_ASSERTD(MPFR_IS_ZERO(x)); + MPFR_SET_ZERO(y); + MPFR_SET_SAME_SIGN(y, x); + MPFR_RET(0); + } + } + + /* tan(x) = x + x^3/3 + ... so the error is < 2^(3*EXP(x)-1) */ + MPFR_FAST_COMPUTE_IF_SMALL_INPUT (y, x, -2 * MPFR_GET_EXP (x), 1, 1, + rnd_mode, {}); + + MPFR_SAVE_EXPO_MARK (expo); + + /* Compute initial precision */ + precy = MPFR_PREC (y); + m = precy + MPFR_INT_CEIL_LOG2 (precy) + 13; + MPFR_ASSERTD (m >= 2); /* needed for the error analysis in algorithms.tex */ + + MPFR_GROUP_INIT_2 (group, m, s, c); + MPFR_ZIV_INIT (loop, m); + for (;;) + { + /* The only way to get an overflow is to get ~ Pi/2 + But the result will be ~ 2^Prec(y). */ + mpfr_sin_cos (s, c, x, MPFR_RNDN); /* err <= 1/2 ulp on s and c */ + mpfr_div (c, s, c, MPFR_RNDN); /* err <= 4 ulps */ + MPFR_ASSERTD (!MPFR_IS_SINGULAR (c)); + if (MPFR_LIKELY (MPFR_CAN_ROUND (c, m - 2, precy, rnd_mode))) + break; + MPFR_ZIV_NEXT (loop, m); + MPFR_GROUP_REPREC_2 (group, m, s, c); + } + MPFR_ZIV_FREE (loop); + inexact = mpfr_set (y, c, rnd_mode); + MPFR_GROUP_CLEAR (group); + + MPFR_SAVE_EXPO_FREE (expo); + return mpfr_check_range (y, inexact, rnd_mode); +} |