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sourceware.org Git - glibc.git/blob - sysdeps/powerpc/powerpc32/power4/fpu/slowexp.c
2 * IBM Accurate Mathematical Library
3 * written by International Business Machines Corp.
4 * Copyright (C) 2001, 2007 Free Software Foundation
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU Lesser General Public License as published by
8 * the Free Software Foundation; either version 2.1 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public License
17 * along with this program; if not, see <http://www.gnu.org/licenses/>.
19 /**************************************************************************/
20 /* MODULE_NAME:slowexp.c */
22 /* FUNCTION:slowexp */
24 /* FILES NEEDED:mpa.h */
27 /*Converting from double precision to Multi-precision and calculating */
29 /**************************************************************************/
30 #include <math_private.h>
34 void __mpexp(mp_no
*x
, mp_no
*y
, int p
);
37 /*Converting from double precision to Multi-precision and calculating e^x */
38 double __slowexp(double x
) {
40 double w
,z
,res
,eps
=3.0e-26;
42 mp_no mpx
, mpy
, mpz
,mpw
,mpeps
,mpcor
;
45 __dbl_mp(x
,&mpx
,p
); /* Convert a double precision number x */
46 /* into a multiple precision number mpx with prec. p. */
47 __mpexp(&mpx
, &mpy
, p
); /* Multi-Precision exponential function */
48 __dbl_mp(eps
,&mpeps
,p
);
49 __mul(&mpeps
,&mpy
,&mpcor
,p
);
50 __add(&mpy
,&mpcor
,&mpw
,p
);
51 __sub(&mpy
,&mpcor
,&mpz
,p
);
52 __mp_dbl(&mpw
, &w
, p
);
53 __mp_dbl(&mpz
, &z
, p
);
55 else { /* if calculating is not exactly */
58 __mpexp(&mpx
, &mpy
, p
);
59 __mp_dbl(&mpy
, &res
, p
);
63 return (double) __ieee754_expl((long double)x
);
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