Imported gcc-4.4.3

[msp430-gcc.git] / mpfr / cosh.c

diff --git a/mpfr/cosh.c b/mpfr/cosh.c
new file mode 100644 (file)
index 0000000..4be37ba
--- /dev/null
+++ b/mpfr/cosh.c
@@ -0,0 +1,126 @@
+/* mpfr_cosh -- hyperbolic cosine
+
+Copyright 2001, 2002, 2004, 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
+Contributed by the Arenaire and Cacao 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 2.1 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.LIB.  If not, 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"
+
+/* The computation of cosh is done by    *
+ *  cosh= 1/2[e^(x)+e^(-x)]              */
+
+int
+mpfr_cosh (mpfr_ptr y, mpfr_srcptr xt , mp_rnd_t rnd_mode)
+{
+  mpfr_t x;
+  int inexact;
+  MPFR_SAVE_EXPO_DECL (expo);
+
+  MPFR_LOG_FUNC (("x[%#R]=%R rnd=%d", xt, xt, rnd_mode),
+                 ("y[%#R]=%R inexact=%d", y, y, inexact));
+
+  if (MPFR_UNLIKELY(MPFR_IS_SINGULAR(xt)))
+    {
+      if (MPFR_IS_NAN(xt))
+        {
+          MPFR_SET_NAN(y);
+          MPFR_RET_NAN;
+        }
+      else if (MPFR_IS_INF(xt))
+        {
+          MPFR_SET_INF(y);
+          MPFR_SET_POS(y);
+          MPFR_RET(0);
+        }
+      else
+        {
+          MPFR_ASSERTD(MPFR_IS_ZERO(xt));
+          return mpfr_set_ui (y, 1, rnd_mode); /* cosh(0) = 1 */
+        }
+    }
+
+  MPFR_SAVE_EXPO_MARK (expo);
+
+  /* cosh(x) = 1+x^2/2 + ... <= 1+x^2 for x <= 2.9828...,
+     thus the error < 2^(2*EXP(x)). If x >= 1, then EXP(x) >= 1,
+     thus the following will always fail. */
+  MPFR_FAST_COMPUTE_IF_SMALL_INPUT (y, __gmpfr_one, -2 * MPFR_GET_EXP (xt), 0,
+                                    1, rnd_mode, inexact = _inexact; goto end);
+
+  MPFR_TMP_INIT_ABS(x, xt);
+  /* General case */
+  {
+    /* Declaration of the intermediary variable */
+    mpfr_t t, te;
+    /* Declaration of the size variable */
+    mp_prec_t Ny = MPFR_PREC(y);   /* Precision of output variable */
+    mp_prec_t Nt;                  /* Precision of the intermediary variable */
+    long int err;                  /* Precision of error */
+    MPFR_ZIV_DECL (loop);
+    MPFR_GROUP_DECL (group);
+
+    /* compute the precision of intermediary variable */
+    /* The optimal number of bits : see algorithms.tex */
+    Nt = Ny + 3 + MPFR_INT_CEIL_LOG2 (Ny);
+
+    /* initialise of intermediary variables */
+    MPFR_GROUP_INIT_2 (group, Nt, t, te);
+
+    /* First computation of cosh */
+    MPFR_ZIV_INIT (loop, Nt);
+    for (;;)
+      {
+        MPFR_BLOCK_DECL (flags);
+
+        /* Compute cosh */
+        MPFR_BLOCK (flags, mpfr_exp (te, x, GMP_RNDD));  /* exp(x) */
+        /* exp can overflow (but not underflow since x>0) */
+        if (MPFR_OVERFLOW (flags))
+          /* cosh(x) > exp(x), cosh(x) underflows too */
+          {
+            inexact = mpfr_overflow (y, rnd_mode, MPFR_SIGN_POS);
+            MPFR_SAVE_EXPO_UPDATE_FLAGS (expo, MPFR_FLAGS_OVERFLOW);
+            break;
+          }
+        mpfr_ui_div (t, 1, te, GMP_RNDU);   /* 1/exp(x) */
+        mpfr_add (t, te, t, GMP_RNDU);      /* exp(x) + 1/exp(x)*/
+        mpfr_div_2ui (t, t, 1, GMP_RNDN);   /* 1/2(exp(x) + 1/exp(x))*/
+
+        /* Estimation of the error */
+        err = Nt - 3;
+        /* Check if we can round */
+        if (MPFR_LIKELY (MPFR_CAN_ROUND (t, err, Ny, rnd_mode)))
+          {
+            inexact = mpfr_set (y, t, rnd_mode);
+            break;
+          }
+
+        /* Actualisation of the precision */
+        MPFR_ZIV_NEXT (loop, Nt);
+        MPFR_GROUP_REPREC_2 (group, Nt, t, te);
+      }
+    MPFR_ZIV_FREE (loop);
+    MPFR_GROUP_CLEAR (group);
+  }
+
+ end:
+  MPFR_SAVE_EXPO_FREE (expo);
+  return mpfr_check_range (y, inexact, rnd_mode);
+}