1 2 /* 3 * IBM Accurate Mathematical Library 4 * written by International Business Machines Corp. 5 * Copyright (C) 2001 Free Software Foundation 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU Lesser General Public License as published by 9 * the Free Software Foundation; either version 2.1 of the License, or 10 * (at your option) any later version. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU Lesser General Public License for more details. 16 * 17 * You should have received a copy of the GNU Lesser General Public License 18 * along with this program; if not, write to the Free Software 19 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 20 */ 21 /******************************************************************/ 22 /* MODULE_NAME: mpatan2.c */ 23 /* */ 24 /* FUNCTIONS:mpatan2 */ 25 /* */ 26 /* FILES NEEDED: mpa.h */ 27 /* mpa.c mpatan.c mpsqrt.c */ 28 /* */ 29 /* Multi-Precision Atan2(y,x) function subroutine, */ 30 /* for precision p >= 4. */ 31 /* y=0 is not permitted if x<=0. No error messages are given. */ 32 /* The relative error of the result is bounded by 44.84*r**(1-p) */ 33 /* if x <= 0, y != 0 and by 37.33*r**(1-p) if x>0. here r=2**24. */ 34 /* */ 35 /******************************************************************/ 36 37 38 39 #include "mpa.h" 40 41 void __mpsqrt(mp_no *, mp_no *, int); 42 void __mpatan(mp_no *, mp_no *, int); 43 44 /* Multi-Precision Atan2(y,x) function subroutine, for p >= 4. */ 45 /* y=0 is not permitted if x<=0. No error messages are given. */ 46 void __mpatan2(mp_no *y, mp_no *x, mp_no *z, int p) { 47 48 static const double ZERO = 0.0, ONE = 1.0; 49 50 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, 51 0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0, 52 0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0}}; 53 mp_no mpt1,mpt2,mpt3; 54 55 56 if (X[0] <= ZERO) { 57 mpone.e = 1; mpone.d[0] = mpone.d[1] = ONE; 58 __dvd(x,y,&mpt1,p); __mul(&mpt1,&mpt1,&mpt2,p); 59 if (mpt1.d[0] != ZERO) mpt1.d[0] = ONE; 60 __add(&mpt2,&mpone,&mpt3,p); __mpsqrt(&mpt3,&mpt2,p); 61 __add(&mpt1,&mpt2,&mpt3,p); mpt3.d[0]=Y[0]; 62 __mpatan(&mpt3,&mpt1,p); __add(&mpt1,&mpt1,z,p); 63 } 64 else 65 { __dvd(y,x,&mpt1,p); 66 __mpatan(&mpt1,z,p); 67 } 68 69 return; 70 } 71