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e4d82761 UD |
1 | /* |
2 | * IBM Accurate Mathematical Library | |
3 | * Copyright (c) International Business Machines Corp., 2001 | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of the GNU Lesser General Public License as published by | |
50944bca | 7 | * the Free Software Foundation; either version 2 of the License, or |
e4d82761 | 8 | * (at your option) any later version. |
50944bca | 9 | * |
e4d82761 UD |
10 | * This program is distributed in the hope that it will be useful, |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | * GNU General Public License for more details. | |
14 | * | |
15 | * You should have received a copy of the GNU Lesser General Public License | |
16 | * along with this program; if not, write to the Free Software | |
50944bca | 17 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
e4d82761 UD |
18 | */ |
19 | /**************************************************************************/ | |
20 | /* MODULE_NAME:slowexp.c */ | |
21 | /* */ | |
50944bca | 22 | /* FUNCTION:slowexp */ |
e4d82761 UD |
23 | /* */ |
24 | /* FILES NEEDED:mpa.h */ | |
25 | /* mpa.c mpexp.c */ | |
26 | /* */ | |
27 | /*Converting from double precision to Multi-precision and calculating */ | |
28 | /* e^x */ | |
29 | /**************************************************************************/ | |
30 | #include "mpa.h" | |
15b3c029 | 31 | #include "math_private.h" |
e4d82761 | 32 | |
ca58f1db | 33 | void __mpexp(mp_no *x, mp_no *y, int p); |
e4d82761 UD |
34 | |
35 | /*Converting from double precision to Multi-precision and calculating e^x */ | |
ca58f1db | 36 | double __slowexp(double x) { |
50944bca UD |
37 | double w,z,res,eps=3.0e-26; |
38 | #if 0 | |
39 | double y; | |
40 | #endif | |
41 | int p; | |
42 | #if 0 | |
43 | int orig,i; | |
44 | #endif | |
e4d82761 | 45 | mp_no mpx, mpy, mpz,mpw,mpeps,mpcor; |
50944bca | 46 | |
e4d82761 | 47 | p=6; |
ca58f1db | 48 | __dbl_mp(x,&mpx,p); /* Convert a double precision number x */ |
e4d82761 | 49 | /* into a multiple precision number mpx with prec. p. */ |
ca58f1db UD |
50 | __mpexp(&mpx, &mpy, p); /* Multi-Precision exponential function */ |
51 | __dbl_mp(eps,&mpeps,p); | |
52 | __mul(&mpeps,&mpy,&mpcor,p); | |
53 | __add(&mpy,&mpcor,&mpw,p); | |
54 | __sub(&mpy,&mpcor,&mpz,p); | |
50944bca UD |
55 | __mp_dbl(&mpw, &w, p); |
56 | __mp_dbl(&mpz, &z, p); | |
e4d82761 UD |
57 | if (w == z) return w; |
58 | else { /* if calculating is not exactly */ | |
59 | p = 32; | |
ca58f1db UD |
60 | __dbl_mp(x,&mpx,p); |
61 | __mpexp(&mpx, &mpy, p); | |
50944bca | 62 | __mp_dbl(&mpy, &res, p); |
e4d82761 UD |
63 | return res; |
64 | } | |
65 | } |