new file function

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@1057 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 151 insertions, 0 deletions

diff --git a/acosh.c b/acosh.c
new file mode 100644
index 000000000..d8a6dfafc
--- /dev/null
+++ b/acosh.c
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+/* mpfr_acosh -- Inverse Hyperbolic Cosine of Unsigned Integer Number
+
+Copyright (C) 1999 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 Library General Public License as published by
+the Free Software Foundation; either version 2 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 Library General Public
+License for more details.
+
+You should have received a copy of the GNU Library 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 acosh is done by
+
+    acosh= ln(x+sqrt(x-1)*sqrt(x+1))
+ */
+
+int mpfr_acosh _PROTO((mpfr_ptr, mpfr_srcptr, mp_rnd_t));
+
+int
+#if __STDC__
+mpfr_acosh (mpfr_ptr y, mpfr_srcptr x , mp_rnd_t rnd_mode) 
+#else
+mpfr_acosh (y, x, rnd_mode)
+     mpfr_ptr y;
+     mpfr_srcptr x;
+     mp_rnd_t rnd_mode;
+#endif
+{
+    
+  /****** Declaration ******/
+
+    /* Variable of Intermediary Calculation*/
+    mpfr_t t;       
+
+    /* Variable of Intermediary Calculation*/
+    mpfr_t ta,tb;
+
+    int round;
+    int boucle;
+    int comp;
+
+    mp_prec_t Nx;   /* Precision of input variable */
+    mp_prec_t Ny;   /* Precision of output variable */
+    mp_prec_t Nt;   /* Precision of Intermediary Calculation variable */
+    mp_prec_t err;  /* Precision of error */
+
+    
+    if (MPFR_IS_NAN(x)) {  MPFR_SET_NAN(y); return 1; }
+    MPFR_CLEAR_NAN(y);
+
+    if (MPFR_IS_INF(x)){ 
+      MPFR_SET_INF(y);
+      if (MPFR_SIGN(y) < 0) MPFR_CHANGE_SIGN(y);
+      return 1;
+    }
+
+    MPFR_CLEAR_INF(y);
+
+    comp=mpfr_cmp_ui(x,1);
+
+    if(comp <= 0){
+      if(comp == 0){
+	MPFR_SET_ZERO(y); /* acosh(1) = 0 */
+	return(0);
+      }
+      else{
+	/*fprintf(stderr,"Function acosh of MPFR is only defined for x=[1,+Inf]");
+	exit(-1);*/
+
+	/*An other strategy if output is not define for input return NaN*/
+	MPFR_SET_NAN(y); return(-1);
+
+      }
+    }
+    else{
+      
+
+        /* Initialisation of the Precision */
+	Nx=MPFR_PREC(x);
+	Ny=MPFR_PREC(y);
+
+	/* compute the size of intermediary variable */
+	if(Ny>=Nx)
+	  Nt=Ny+2*(BITS_PER_CHAR); 
+	else
+	  Nt=Nx+2*(BITS_PER_CHAR); 
+	  
+	  boucle=1;
+
+	    /* initialise of intermediary	variable */
+	    mpfr_init2(t,Nt);                
+	    mpfr_init2(ta,Nt);             
+	    mpfr_init2(tb,Nt);             
+
+	  while(boucle==1){
+
+
+	    /* compute acosh */
+
+	    mpfr_add_ui(ta,x,1,GMP_RNDN);  /* (x+1) */
+	    mpfr_sub_ui(tb,x,1,GMP_RNDN);  /* (x-1) */
+	    mpfr_sqrt(ta,ta,GMP_RNDN);     /* sqrt(x+1) */
+	    mpfr_sqrt(tb,tb,GMP_RNDN);     /* sqrt(x-1) */
+	    mpfr_mul(t,ta,tb,GMP_RNDN);    /* sqrt(x+1)*sqrt(x-1) */
+	    mpfr_add(t,t,x,GMP_RNDN);      /* sqrt(x+1)*sqrt(x-1)+x */
+	    mpfr_log(t,t,GMP_RNDN);        /* ln(sqrt(x+1)*sqrt(x-1)+x)*/
+	    
+	    err=Nt-1-MAX(0,-MPFR_EXP(t));
+
+	    round=mpfr_can_round(t,err,GMP_RNDN,rnd_mode,Ny);
+
+	    if(round == 1){
+	      mpfr_set(y,t,rnd_mode);
+	      boucle=0;
+	    }
+	    else{
+	      Nt=Nt+10;
+	      /* initialise of intermediary	variable */
+	      mpfr_set_prec(t,Nt);                
+	      mpfr_set_prec(ta,Nt);   
+	      mpfr_set_prec(tb,Nt);             
+
+	      boucle=1;
+	    }
+	    
+	  }
+    
+	  mpfr_clear(t);
+	  mpfr_clear(ta);
+	  mpfr_clear(tb);
+          return(1);
+      
+ 
+    }
+}