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-rw-r--r-- | cosh.c | 133 |
1 files changed, 133 insertions, 0 deletions
@@ -0,0 +1,133 @@ +/* mpfr_cosh -- 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 cosh is done by + + cosh= 1/2[e^(x)+e^(-x)] + */ +int mpfr_cosh _PROTO((mpfr_ptr, mpfr_srcptr, mp_rnd_t)); + +int +#if __STDC__ +mpfr_cosh (mpfr_ptr y, mpfr_srcptr x , mp_rnd_t rnd_mode) +#else +mpfr_cosh (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 te,ti; + + int round; + int boucle; + + 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); + + if(!MPFR_NOTZERO(x)){ + mpfr_set_ui(y,1,GMP_RNDN); /* cosh(0) = 1 */ + return(0); + } + 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(te,Nt); + mpfr_init2(ti,Nt); + + while(boucle==1){ + + + /* compute cosh */ + mpfr_exp(te,x,GMP_RNDN); /* exp(x) */ + mpfr_ui_div(ti,1,te,GMP_RNDN); /* 1/exp(x) */ + mpfr_add(t,te,ti,GMP_RNDN); /* exp(x) + 1/exp(x)*/ + mpfr_div_2exp(t,t,1,GMP_RNDN); /* 1/2(exp(x) + 1/exp(x))*/ + + err=Nt-1; + + 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; + /* re-initialise of intermediary variable */ + mpfr_set_prec(t,Nt); + mpfr_set_prec(te,Nt); + mpfr_set_prec(ti,Nt); + + boucle=1; + } + + + } + + mpfr_clear(t); + mpfr_clear(ti); + mpfr_clear(te); + return(1); + + + + } +} |