File: [local] / OpenXM_contrib / gmp / mpfr / Attic / hypot.c (download)
Revision 1.1.1.1 (vendor branch), Mon Aug 25 16:06:08 2003 UTC (21 years, 1 month ago) by ohara
Branch: GMP
CVS Tags: VERSION_4_1_2, RELEASE_1_2_3, RELEASE_1_2_2_KNOPPIX_b, RELEASE_1_2_2_KNOPPIX Changes since 1.1: +0 -0
lines
Import gmp 4.1.2
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/* mpfr_hypot -- Euclidean distance
Copyright 2001, 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 <stdio.h>
#include <stdlib.h>
#include "gmp.h"
#include "gmp-impl.h"
#include "mpfr.h"
#include "mpfr-impl.h"
/* The computation of hypot of x and y is done by
hypot(x,y)= sqrt(x^2+y^2) = z
*/
int
mpfr_hypot (mpfr_ptr z, mpfr_srcptr x ,mpfr_srcptr y , mp_rnd_t rnd_mode)
{
int inexact;
/* Flag calcul exacte */
int not_exact=0;
/* particular cases */
if (MPFR_IS_NAN(x) || MPFR_IS_NAN(y))
{
MPFR_SET_NAN(z);
MPFR_RET_NAN;
}
MPFR_CLEAR_NAN(z);
if (MPFR_IS_INF(x) || MPFR_IS_INF(y))
{
MPFR_SET_INF(z);
MPFR_SET_POS(z);
MPFR_RET(0);
}
MPFR_CLEAR_INF(z);
if(MPFR_IS_ZERO(x))
return mpfr_abs (z, y, rnd_mode);
if(MPFR_IS_ZERO(y))
return mpfr_abs (z, x, rnd_mode);
/* General case */
{
/* Declaration of the intermediary variable */
mpfr_t t, te,ti;
/* 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 Nz = MPFR_PREC(z); /* Precision of input variable */
int Nt; /* Precision of the intermediary variable */
long int err; /* Precision of error */
/* compute the precision of intermediary variable */
Nt=MAX(MAX(Nx,Ny),Nz);
/* compute the size of intermediary variable -- see algorithms.ps */
Nt=Nt+2+_mpfr_ceil_log2(Nt);
/* initialise the intermediary variables */
mpfr_init(t);
mpfr_init(te);
mpfr_init(ti);
/* Hypot */
do {
not_exact=0;
/* reactualisation of the precision */
mpfr_set_prec(t,Nt);
mpfr_set_prec(te,Nt);
mpfr_set_prec(ti,Nt);
/* computations of hypot */
if(mpfr_mul(te,x,x,GMP_RNDN)) /* x^2 */
not_exact=1;
if(mpfr_mul(ti,y,y,GMP_RNDN)) /* y^2 */
not_exact=1;
if(mpfr_add(t,te,ti,GMP_RNDD)) /*x^2+y^2*/
not_exact=1;
if(mpfr_sqrt(t,t,GMP_RNDN)) /* sqrt(x^2+y^2)*/
not_exact=1;
/* estimation of the error */
err=Nt-(2);
Nt += 10;
if(Nt<0)Nt=0;
} while ((err <0) || ((!mpfr_can_round(t,err,GMP_RNDN,rnd_mode,Nz)) && not_exact));
inexact = mpfr_set (z, t, rnd_mode);
mpfr_clear(t);
mpfr_clear(ti);
mpfr_clear(te);
}
if (not_exact == 0 && inexact == 0)
return 0;
if (not_exact != 0 && inexact == 0)
return 1;
return inexact;
}