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diff --git a/mpfr/expm1.c b/mpfr/expm1.c
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+/* mpfr_expm1 -- Compute exp(x)-1
+
+Copyright (C) 2001 Free Software Foundation.
+
+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"
+
+ /* The computation of expm1 is done by
+
+ expm1(x)=exp(x)-1
+ */
+
+int
+mpfr_expm1 (mpfr_ptr y, mpfr_srcptr x , mp_rnd_t rnd_mode)
+{
+
+ int inexact = 0;
+
+ if (MPFR_IS_NAN(x))
+ {
+ MPFR_SET_NAN(y);
+ return 1;
+ }
+ MPFR_CLEAR_NAN(y);
+
+
+ /* check for inf or -inf (expm1(-inf)=-1) */
+ if (MPFR_IS_INF(x))
+ {
+ if(MPFR_SIGN(x) > 0)
+ {
+ MPFR_SET_INF(y);
+ MPFR_SET_SAME_SIGN(y,x);
+ return 0;
+ }
+ else
+ return mpfr_set_ui(y,-1,rnd_mode);
+ }
+
+ MPFR_CLEAR_INF(y);
+
+
+ if(!MPFR_NOTZERO(x))
+ {
+ MPFR_SET_ZERO(y); /* expm1(+/- 0) = +/- 0 */
+ MPFR_SET_SAME_SIGN(y,x);
+ return 0;
+ }
+
+ /* General case */
+ {
+ /* Declaration of the intermediary variable */
+ mpfr_t te,t;
+
+ /* Declaration of the size variable */
+ mp_prec_t Nx = MPFR_PREC(x); /* Precision of input variable */
+ mp_prec_t Ny = MPFR_PREC(y); /* 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+5+_mpfr_ceil_log2(Nt);
+
+ /* initialise of intermediary variable */
+ mpfr_init(t);
+ mpfr_init(te);
+
+ /* First computation of cosh */
+ do {
+
+ /* reactualisation of the precision */
+ mpfr_set_prec(t,Nt);
+ mpfr_set_prec(te,Nt);
+
+ /* compute expm1 */
+ mpfr_exp(te,x,GMP_RNDN); /* exp(x)*/
+ mpfr_sub_ui(t,te,1,GMP_RNDN); /* exp(x)-1 */
+
+ /* estimation of the error */
+ /*err=Nt-(_mpfr_ceil_log2(1+pow(2,MPFR_EXP(te)-MPFR_EXP(t))));*/
+ err=Nt-(MAX(MPFR_EXP(te)-MPFR_EXP(t),0)+1);
+
+ /* actualisation of the precision */
+ Nt += 10;
+
+ } while ((err <0) || !mpfr_can_round(t,err,GMP_RNDN,rnd_mode,Ny));
+
+ inexact = mpfr_set(y,t,rnd_mode);
+
+ mpfr_clear(t);
+ mpfr_clear(te);
+ }
+ return inexact;
+}