mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-27 23:40:10 +00:00
61 lines
2.5 KiB
C
61 lines
2.5 KiB
C
|
|
||
|
|
/*
|
||
|
|
* IBM Accurate Mathematical Library
|
||
|
|
* Copyright (c) International Business Machines Corp., 2001
|
||
|
|
*
|
||
|
|
* This program 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 of the License, or
|
||
|
|
* (at your option) any later version.
|
||
|
|
*
|
||
|
|
* This program 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 General Public License for more details.
|
||
|
|
*
|
||
|
|
* You should have received a copy of the GNU Lesser General Public License
|
||
|
|
* along with this program; if not, write to the Free Software
|
||
|
|
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
|
||
|
|
*/
|
||
|
|
/**************************************************************************/
|
||
|
|
/* MODULE_NAME:slowexp.c */
|
||
|
|
/* */
|
||
|
|
/* FUNCTION:slowexp */
|
||
|
|
/* */
|
||
|
|
/* FILES NEEDED:mpa.h */
|
||
|
|
/* mpa.c mpexp.c */
|
||
|
|
/* */
|
||
|
|
/*Converting from double precision to Multi-precision and calculating */
|
||
|
|
/* e^x */
|
||
|
|
/**************************************************************************/
|
||
|
|
#include "mpa.h"
|
||
|
|
|
||
|
|
void mpexp(mp_no *x, mp_no *y, int p);
|
||
|
|
|
||
|
|
/*Converting from double precision to Multi-precision and calculating e^x */
|
||
|
|
double slowexp(double x) {
|
||
|
|
double y,w,z,res,eps=3.0e-26;
|
||
|
|
int orig,i,p;
|
||
|
|
mp_no mpx, mpy, mpz,mpw,mpeps,mpcor;
|
||
|
|
|
||
|
|
p=6;
|
||
|
|
dbl_mp(x,&mpx,p); /* Convert a double precision number x */
|
||
|
|
/* into a multiple precision number mpx with prec. p. */
|
||
|
|
mpexp(&mpx, &mpy, p); /* Multi-Precision exponential function */
|
||
|
|
dbl_mp(eps,&mpeps,p);
|
||
|
|
mul(&mpeps,&mpy,&mpcor,p);
|
||
|
|
add(&mpy,&mpcor,&mpw,p);
|
||
|
|
sub(&mpy,&mpcor,&mpz,p);
|
||
|
|
mp_dbl(&mpw, &w, p);
|
||
|
|
mp_dbl(&mpz, &z, p);
|
||
|
|
if (w == z) return w;
|
||
|
|
else { /* if calculating is not exactly */
|
||
|
|
p = 32;
|
||
|
|
dbl_mp(x,&mpx,p);
|
||
|
|
mpexp(&mpx, &mpy, p);
|
||
|
|
mp_dbl(&mpy, &res, p);
|
||
|
|
return res;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|