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Diffstat (limited to 'sysdeps/ieee754/dbl-64/mpexp.c')
| -rw-r--r-- | sysdeps/ieee754/dbl-64/mpexp.c | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/sysdeps/ieee754/dbl-64/mpexp.c b/sysdeps/ieee754/dbl-64/mpexp.c new file mode 100644 index 0000000..2d11675 --- /dev/null +++ b/sysdeps/ieee754/dbl-64/mpexp.c @@ -0,0 +1,105 @@ + +/* + * 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:mpexp.c */ +/* */ +/* FUNCTIONS: mpexp */ +/* */ +/* FILES NEEDED: mpa.h endian.h mpexp.h */ +/* mpa.c */ +/* */ +/* Multi-Precision exponential function subroutine */ +/* ( for p >= 4, 2**(-55) <= abs(x) <= 1024 ). */ +/*************************************************************************/ + +#include "endian.h" +#include "mpa.h" +#include "mpexp.h" + +/* Multi-Precision exponential function subroutine (for p >= 4, */ +/* 2**(-55) <= abs(x) <= 1024). */ +void mpexp(mp_no *x, mp_no *y, int p) { + + int i,j,k,m,m1,m2,n; + double a,b; + static const int np[33] = {0,0,0,0,3,3,4,4,5,4,4,5,5,5,6,6,6,6,6,6, + 6,6,6,6,7,7,7,7,8,8,8,8,8}; + static const int m1p[33]= {0,0,0,0,17,23,23,28,27,38,42,39,43,47,43,47,50,54, + 57,60,64,67,71,74,68,71,74,77,70,73,76,78,81}; + static const int m1np[7][18] = { + { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, + { 0, 0, 0, 0,36,48,60,72, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, + { 0, 0, 0, 0,24,32,40,48,56,64,72, 0, 0, 0, 0, 0, 0, 0}, + { 0, 0, 0, 0,17,23,29,35,41,47,53,59,65, 0, 0, 0, 0, 0}, + { 0, 0, 0, 0, 0, 0,23,28,33,38,42,47,52,57,62,66, 0, 0}, + { 0, 0, 0, 0, 0, 0, 0, 0,27, 0, 0,39,43,47,51,55,59,63}, + { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,43,47,50,54}}; + mp_no mpone = {0, 0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0, + 0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0, + 0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,}; + mp_no mpk = {0, 0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0, + 0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0, + 0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,}; + mp_no mps,mpak,mpt1,mpt2; + + /* Choose m,n and compute a=2**(-m) */ + n = np[p]; m1 = m1p[p]; a = twomm1[p].d; + for (i=0; i<EX; i++) a *= RADIXI; + for ( ; i>EX; i--) a *= RADIX; + b = X[1]*RADIXI; m2 = 24*EX; + for (; b<HALF; m2--) { a *= TWO; b *= TWO; } + if (b == HALF) { + for (i=2; i<=p; i++) { if (X[i]!=ZERO) break; } + if (i==p+1) { m2--; a *= TWO; } + } + if ((m=m1+m2) <= 0) { + m=0; a=ONE; + for (i=n-1; i>0; i--,n--) { if (m1np[i][p]+m2>0) break; } + } + + /* Compute s=x*2**(-m). Put result in mps */ + dbl_mp(a,&mpt1,p); + mul(x,&mpt1,&mps,p); + + /* Evaluate the polynomial. Put result in mpt2 */ + mpone.e=1; mpone.d[0]=ONE; mpone.d[1]=ONE; + mpk.e = 1; mpk.d[0] = ONE; mpk.d[1]=nn[n].d; + dvd(&mps,&mpk,&mpt1,p); + add(&mpone,&mpt1,&mpak,p); + for (k=n-1; k>1; k--) { + mul(&mps,&mpak,&mpt1,p); + mpk.d[1]=nn[k].d; + dvd(&mpt1,&mpk,&mpt2,p); + add(&mpone,&mpt2,&mpak,p); + } + mul(&mps,&mpak,&mpt1,p); + add(&mpone,&mpt1,&mpt2,p); + + /* Raise polynomial value to the power of 2**m. Put result in y */ + for (k=0,j=0; k<m; ) { + mul(&mpt2,&mpt2,&mpt1,p); k++; + if (k==m) { j=1; break; } + mul(&mpt1,&mpt1,&mpt2,p); k++; + } + if (j) cpy(&mpt1,y,p); + else cpy(&mpt2,y,p); + return; +} + |