Files log_base_*.c renamed.

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@1629 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 147 insertions, 0 deletions

diff --git a/log10.c b/log10.c
new file mode 100644
index 000000000..b1e5e7d6f
--- /dev/null
+++ b/log10.c
@@ -0,0 +1,147 @@
+/* mpfr_log10 -- log in base 10
+
+Copyright (C) 2001 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 <stdio.h>
+#include "gmp.h"
+#include "gmp-impl.h"
+#include "mpfr.h"
+#include "mpfr-impl.h"
+
+ /* The computation of r=log10(a)
+
+    r=log10(a)=log(a)/log(10)
+ */
+
+int
+mpfr_log10 (mpfr_ptr r, mpfr_srcptr a , mp_rnd_t rnd_mode) 
+{
+
+  int inexact = 0;
+
+  /* If a is NaN, the result is NaN */
+  if (MPFR_IS_NAN(a))
+    {
+      MPFR_SET_NAN(r);
+      MPFR_RET_NAN;
+    }
+
+ /* If a is negative, the result is NaN */
+  if (MPFR_SIGN(a) < 0)
+    {
+      if (!MPFR_IS_INF(a) && MPFR_IS_ZERO(a))
+	{
+	  MPFR_CLEAR_NAN(r);
+	  MPFR_SET_INF(r); 
+	  if (MPFR_SIGN(r) > 0)
+	    MPFR_CHANGE_SIGN(r);
+	  return 0; 
+      }
+      else
+	{
+	  MPFR_SET_NAN(r);
+	  MPFR_RET_NAN;
+	}
+    }
+
+  MPFR_CLEAR_NAN(r);
+
+  /* check for infinity before zero */
+  if (MPFR_IS_INF(a))
+    {
+      /* only +Inf can go here */
+      MPFR_SET_INF(r);
+      if(MPFR_SIGN(r) < 0)
+        MPFR_CHANGE_SIGN(r);
+      return 0;
+    }
+
+  /* Now we can clear the flags without damage even if r == a */
+
+  MPFR_CLEAR_INF(r); 
+
+  if (MPFR_IS_ZERO(a)) 
+    {
+      MPFR_SET_INF(r); 
+      if (MPFR_SIGN(r) > 0)
+	MPFR_CHANGE_SIGN(r);
+       /* Execption GMP*/
+      return 0; 
+    }
+
+  /* If a is 1, the result is 0 */
+  if (mpfr_cmp_ui(a,1) == 0)
+    {
+      MPFR_SET_SAME_SIGN(r,a);
+      MPFR_SET_ZERO(r);
+      return 0; 
+    }
+
+
+  /* General case */
+  {
+    /* Declaration of the intermediary variable */
+    mpfr_t t, tt;
+
+    /* Declaration of the size variable */
+    mp_prec_t Nx = MPFR_PREC(a);   /* Precision of input variable */
+    mp_prec_t Ny = MPFR_PREC(r);   /* Precision of input variable */
+    
+    mp_prec_t Nt;   /* Precision of the intermediary variable */
+    long int err;  /* Precision of error */
+                
+    /* compute the precision of intermediary variable */
+    Nt=MAX(Nx,Ny);
+    /* the optimal number of bits : see algorithms.ps */
+    Nt=Nt+4+_mpfr_ceil_log2(Nt);
+
+    /* initialise of intermediary	variable */
+    mpfr_init(t);             
+    mpfr_init(tt);             
+
+    
+    /* First computation of log10 */
+    do {
+
+      /* reactualisation of the precision */
+      mpfr_set_prec(t,Nt);             
+      mpfr_set_prec(tt,Nt);             
+      
+      /* compute log10 */
+      mpfr_set_ui(t,10,GMP_RNDN);  /* 10 */
+      mpfr_log(t,t,GMP_RNDD);       /* log(10) */
+      mpfr_log(tt,a,GMP_RNDN);      /* log(a) */
+      mpfr_div(t,tt,t,GMP_RNDN);    /* log(a)/log(10) */
+
+
+      /* estimation of the error */
+      err=Nt-4;
+
+      /* actualisation of the precision */
+      Nt += 10;
+    } while ((err<0) || !mpfr_can_round(t,err,GMP_RNDN,rnd_mode,Ny));
+ 
+      inexact = mpfr_set(r,t,rnd_mode);
+
+      mpfr_clear(t);
+      mpfr_clear(tt);
+  }
+  return inexact;
+}