| /* |
| * IBM Accurate Mathematical Library |
| * written by International Business Machines Corp. |
| * Copyright (C) 2001 Free Software Foundation |
| * |
| * 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 2.1 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 Lesser 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" |
| #include "math_private.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 w,z,res,eps=3.0e-26; |
| #if 0 |
| double y; |
| #endif |
| int p; |
| #if 0 |
| int orig,i; |
| #endif |
| 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; |
| } |
| } |