new version (adapted from sin.c)

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@1743 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 99 insertions, 0 deletions

diff --git a/sin_cos.c b/sin_cos.c
new file mode 100644
index 000000000..93968cf1f
--- /dev/null
+++ b/sin_cos.c
@@ -0,0 +1,99 @@
+/* mpfr_sin_cos -- sine and cosine of a floating-point number
+
+Copyright 2002 Free Software Foundation, Inc.
+
+This file is part of the MPFR Library.
+
+The 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 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 MPFR Library; see the file COPYING.LIB.  If not, write to
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+MA 02111-1307, USA. */
+
+#include "gmp.h"
+#include "gmp-impl.h"
+#include "mpfr.h"
+#include "mpfr-impl.h"
+
+/* (y, z) <- (sin(x), cos(x)), return value is 0 iff both results are exact */
+int 
+mpfr_sin_cos (mpfr_ptr y, mpfr_ptr z, mpfr_srcptr x, mp_rnd_t rnd_mode) 
+{
+  int prec, m, ok, e, inexact, neg;
+  mpfr_t c, k;
+
+  if (MPFR_IS_NAN(x) || MPFR_IS_INF(x))
+    {
+      MPFR_SET_NAN(y);
+      MPFR_SET_NAN(z);
+      MPFR_RET_NAN;
+    }
+
+  if (MPFR_IS_ZERO(x))
+    {
+      MPFR_CLEAR_FLAGS(y);
+      MPFR_SET_ZERO(y);
+      MPFR_SET_SAME_SIGN(y, x);
+      mpfr_set_ui (z, 1, GMP_RNDN);
+      MPFR_RET(0);
+    }
+
+  prec = MAX(MPFR_PREC(y), MPFR_PREC(z));
+  m = prec + _mpfr_ceil_log2 ((double) prec) + ABS(MPFR_EXP(x)) + 13;
+
+  mpfr_init2 (c, m);
+  mpfr_init2 (k, m);
+
+  /* first determine sign */
+  mpfr_const_pi (c, GMP_RNDN);
+  mpfr_mul_2ui (c, c, 1, GMP_RNDN); /* 2*Pi */
+  mpfr_div (k, x, c, GMP_RNDN);      /* x/(2*Pi) */
+  mpfr_floor (k, k);                 /* floor(x/(2*Pi)) */
+  mpfr_mul (c, k, c, GMP_RNDN);
+  mpfr_sub (k, x, c, GMP_RNDN);      /* 0 <= k < 2*Pi */
+  mpfr_const_pi (c, GMP_RNDN); /* cached */
+  neg = mpfr_cmp (k, c) > 0;
+  mpfr_clear (k);
+
+  do
+    {
+      mpfr_cos (c, x, GMP_RNDZ);
+      if ((ok = mpfr_can_round (c, m, GMP_RNDZ, rnd_mode, MPFR_PREC(z))))
+        {
+          inexact = mpfr_set (z, c, rnd_mode);
+          mpfr_mul (c, c, c, GMP_RNDU);
+          mpfr_ui_sub (c, 1, c, GMP_RNDN);
+          e = 2 + (-MPFR_EXP(c)) / 2;
+          mpfr_sqrt (c, c, GMP_RNDN);
+          if (neg)
+            mpfr_neg (c, c, GMP_RNDN);
+
+          /* the absolute error on c is at most 2^(e-m) = 2^(EXP(c)-err) */
+          e = MPFR_EXP(c) + m - e;
+          ok = (e >= 0) && mpfr_can_round (c, e, GMP_RNDN, rnd_mode,
+                                           MPFR_PREC(y));
+        }
+
+      if (ok == 0)
+	{
+	  m += _mpfr_ceil_log2 ((double) m);
+	  mpfr_set_prec (c, m);
+	}
+    }
+  while (ok == 0);
+
+  inexact = mpfr_set (y, c, rnd_mode) || inexact;
+
+  mpfr_clear (c);
+
+  return inexact; /* inexact */
+}