diff options
Diffstat (limited to 'sysdeps/ieee754/dbl-64/mpatan.c')
| -rw-r--r-- | sysdeps/ieee754/dbl-64/mpatan.c | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/sysdeps/ieee754/dbl-64/mpatan.c b/sysdeps/ieee754/dbl-64/mpatan.c new file mode 100644 index 0000000000..b10775def6 --- /dev/null +++ b/sysdeps/ieee754/dbl-64/mpatan.c @@ -0,0 +1,101 @@ + +/* + * 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:mpatan.c */ +/* */ +/* FUNCTIONS:mpatan */ +/* */ +/* FILES NEEDED: mpa.h endian.h mpatan.h */ +/* mpa.c */ +/* */ +/* Multi-Precision Atan function subroutine, for precision p >= 4.*/ +/* The relative error of the result is bounded by 34.32*r**(1-p), */ +/* where r=2**24. */ +/******************************************************************/ + +#include "endian.h" +#include "mpa.h" +void mpsqrt(mp_no *, mp_no *, int); + +void mpatan(mp_no *x, mp_no *y, int p) { +#include "mpatan.h" + + int i,m,n; + double dx; + 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,}, + mptwo = {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,}, + mptwoim1 = {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,mpsm,mpt,mpt1,mpt2,mpt3; + + /* Choose m and initiate mpone, mptwo & mptwoim1 */ + if (EX>0) m=7; + else if (EX<0) m=0; + else { + mp_dbl(x,&dx,p); dx=ABS(dx); + for (m=6; m>0; m--) + {if (dx>xm[m].d) break;} + } + mpone.e = mptwo.e = mptwoim1.e = 1; + mpone.d[0] = mpone.d[1] = mptwo.d[0] = mptwoim1.d[0] = ONE; + mptwo.d[1] = TWO; + + /* Reduce x m times */ + mul(x,x,&mpsm,p); + if (m==0) cpy(x,&mps,p); + else { + for (i=0; i<m; i++) { + add(&mpone,&mpsm,&mpt1,p); + mpsqrt(&mpt1,&mpt2,p); + add(&mpt2,&mpt2,&mpt1,p); + add(&mptwo,&mpsm,&mpt2,p); + add(&mpt1,&mpt2,&mpt3,p); + dvd(&mpsm,&mpt3,&mpt1,p); + cpy(&mpt1,&mpsm,p); + } + mpsqrt(&mpsm,&mps,p); mps.d[0] = X[0]; + } + + /* Evaluate a truncated power series for Atan(s) */ + n=np[p]; mptwoim1.d[1] = twonm1[p].d; + dvd(&mpsm,&mptwoim1,&mpt,p); + for (i=n-1; i>1; i--) { + mptwoim1.d[1] -= TWO; + dvd(&mpsm,&mptwoim1,&mpt1,p); + mul(&mpsm,&mpt,&mpt2,p); + sub(&mpt1,&mpt2,&mpt,p); + } + mul(&mps,&mpt,&mpt1,p); + sub(&mps,&mpt1,&mpt,p); + + /* Compute Atan(x) */ + mptwoim1.d[1] = twom[m].d; + mul(&mptwoim1,&mpt,y,p); + + return; +} |