diff options
Diffstat (limited to 'sysdeps/ieee754/dbl-64/slowexp.c')
| -rw-r--r-- | sysdeps/ieee754/dbl-64/slowexp.c | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/sysdeps/ieee754/dbl-64/slowexp.c b/sysdeps/ieee754/dbl-64/slowexp.c new file mode 100644 index 0000000000..d394dc3438 --- /dev/null +++ b/sysdeps/ieee754/dbl-64/slowexp.c @@ -0,0 +1,60 @@ + +/* + * 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; + } +} + |