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Annotation of OpenXM_contrib/gmp/mpfr/agm.c, Revision 1.1

1.1     ! maekawa     1: /* mpfr_agm -- arithmetic-geometric mean of two floating-point numbers
        !             2:
        !             3: Copyright (C) 1999 PolKA project, Inria Lorraine and Loria
        !             4:
        !             5: This file is part of the MPFR Library.
        !             6:
        !             7: The MPFR Library is free software; you can redistribute it and/or modify
        !             8: it under the terms of the GNU Library General Public License as published by
        !             9: the Free Software Foundation; either version 2 of the License, or (at your
        !            10: option) any later version.
        !            11:
        !            12: The MPFR Library is distributed in the hope that it will be useful, but
        !            13: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
        !            14: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
        !            15: License for more details.
        !            16:
        !            17: You should have received a copy of the GNU Library General Public License
        !            18: along with the MPFR Library; see the file COPYING.LIB.  If not, write to
        !            19: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
        !            20: MA 02111-1307, USA. */
        !            21:
        !            22: #include <stdio.h>
        !            23: #include <math.h>
        !            24: #include "gmp.h"
        !            25: #include "gmp-impl.h"
        !            26: #include "mpfr.h"
        !            27:
        !            28:
        !            29: /*Memory gestion */
        !            30: #define MON_INIT(xp, x, p, s) xp = (mp_ptr) TMP_ALLOC(s*BYTES_PER_MP_LIMB);    x -> _mp_prec = p; x -> _mp_d = xp; x -> _mp_size = s; x -> _mp_exp = 0;
        !            31:
        !            32:
        !            33:
        !            34:
        !            35: void
        !            36: #ifdef __STDC__
        !            37: mpfr_agm(mpfr_ptr r, mpfr_srcptr op2, mpfr_srcptr op1, unsigned char rnd_mode)
        !            38: #else
        !            39: mpfr_agm(r, a, b, rnd_mode)
        !            40:      mpfr_ptr r;
        !            41:      mpfr_srcptr a;
        !            42:      mpfr_srcptr b;
        !            43:      unsigned char rnd_mode;
        !            44: #endif
        !            45: {
        !            46:   int s, p, q, go_on;
        !            47:   double uo, vo;
        !            48:   mp_limb_t *up, *vp, *tmpp, *tmpup, *tmpvp, *ap, *bp;
        !            49:   mpfr_t u, v, tmp, tmpu, tmpv, a, b;
        !            50:   TMP_DECL(marker1);
        !            51:   TMP_DECL(marker2);
        !            52:
        !            53:
        !            54:   /* If a or b is NaN, the result is NaN */
        !            55:   if (FLAG_NAN(op1) || FLAG_NAN(op2))
        !            56:     { SET_NAN(r); return; }
        !            57:
        !            58:
        !            59:   /* If a or b is negative, the result is NaN */
        !            60:   if ((SIGN(op1)<0)||(SIGN(op2)<0))
        !            61:     { SET_NAN(r); return; }
        !            62:
        !            63:
        !            64:
        !            65:   /* If a or b is 0, the result is 0 */
        !            66:   if ((SIGN(op1)==0)||(SIGN(op2)==0))
        !            67:     { SET_ZERO(r);
        !            68:     return;
        !            69:     }
        !            70:
        !            71:  /* precision of the following calculus */
        !            72:   q = PREC(r);
        !            73:   p = q + 15;
        !            74:
        !            75:
        !            76:   /* Initialisations */
        !            77:   go_on=1;
        !            78:
        !            79:   TMP_MARK(marker1);
        !            80:   s=(p-1)/BITS_PER_MP_LIMB+1;
        !            81:   MON_INIT(ap, a, p, s);
        !            82:   MON_INIT(bp, b, p, s);
        !            83:   TMP_MARK(marker2);
        !            84:   MON_INIT(up, u, p, s);
        !            85:   MON_INIT(vp, v, p, s);
        !            86:   MON_INIT(tmpup, tmpu, p, s);
        !            87:   MON_INIT(tmpvp, tmpv, p, s);
        !            88:   MON_INIT(tmpp, tmp, p, s);
        !            89:
        !            90:
        !            91:
        !            92:   /* b and a will be the 2 operands but I want b>= a */
        !            93:   if (mpfr_cmp(op1,op2) > 0) {
        !            94:     mpfr_set(b,op1,GMP_RNDN); mpfr_set(a,op2,GMP_RNDN);
        !            95:   }
        !            96:   else {
        !            97:     mpfr_set(b,op2,GMP_RNDN); mpfr_set(a,op1,GMP_RNDN);
        !            98:   }
        !            99:
        !           100:   vo=mpfr_get_d(b);
        !           101:   uo=mpfr_get_d(a);
        !           102:
        !           103:   mpfr_set(u,a,GMP_RNDN);
        !           104:   mpfr_set(v,b,GMP_RNDN);
        !           105:
        !           106:
        !           107:   /* Main loop */
        !           108:
        !           109:   while (go_on) {
        !           110:     int err,  eq, can_round;
        !           111:
        !           112:     eq=0;
        !           113:
        !           114:     err=ceil((3.0/2.0*log((double)p)/log(2.0)+1.0)*exp(-(double)p*log(2.0))+3.0*exp(-2.0*(double)p*uo*log(2.0)/(vo-uo)));
        !           115:     if(p-err-3<=q) {
        !           116:       p=q+err+4;
        !           117:       err=ceil((3.0/2.0*log((double)p)/log(2.0)+1.0)*exp(-(double)p*log(2.0))+3.0*exp(-2.0*(double)p*uo*log(2.0)/(vo-uo)));
        !           118:     }
        !           119:
        !           120:     /* Calculus of un and vn */
        !           121:     while (eq<=p-2) {
        !           122:       mpfr_mul(tmp,u,v,GMP_RNDN);
        !           123:       mpfr_sqrt(tmpu,tmp,GMP_RNDN);
        !           124:       mpfr_add(tmp,u,v,GMP_RNDN);
        !           125:       mpfr_div_2exp(tmpv,tmp,1,GMP_RNDN);
        !           126:       mpfr_set(u,tmpu,GMP_RNDN);
        !           127:       mpfr_set(v,tmpv,GMP_RNDN);
        !           128:       if (mpfr_cmp(v,u)>=0)
        !           129:        eq=mpfr_cmp2(v,u);
        !           130:       else
        !           131:        eq=mpfr_cmp2(u,v);
        !           132:     }
        !           133:
        !           134:     /*  printf("avant can_round %i bits faux\n v : ",err+3);
        !           135:        mpfr_print_raw(v); printf("\n u : ");
        !           136:        mpfr_print_raw(u);printf("\n");*/
        !           137:
        !           138:
        !           139:     /* Roundability of the result */
        !           140:       can_round=mpfr_can_round(v,p-err-3,GMP_RNDN,rnd_mode,q);
        !           141:
        !           142:       if (can_round)
        !           143:        go_on=0;
        !           144:
        !           145:       else {
        !           146:          go_on=1;
        !           147:          p+=5;
        !           148:          TMP_FREE(marker2);
        !           149:          TMP_MARK(marker2);
        !           150:          s=(p-1)/BITS_PER_MP_LIMB+1;
        !           151:          MON_INIT(up, u, p, s);
        !           152:          MON_INIT(vp, v, p, s);
        !           153:          MON_INIT(tmpup, tmpu, p, s);
        !           154:          MON_INIT(tmpvp, tmpv, p, s);
        !           155:          MON_INIT(tmpp, tmp, p, s);
        !           156:          mpfr_set(u,a,GMP_RNDN);
        !           157:          mpfr_set(v,b,GMP_RNDN);
        !           158:       }
        !           159:   }
        !           160:   /* End of while */
        !           161:
        !           162:   /* Setting of the result */
        !           163:
        !           164:     mpfr_set(r,v,rnd_mode);
        !           165:
        !           166:
        !           167:   /* Let's clean */
        !           168:     TMP_FREE(marker1);
        !           169:
        !           170:   return ;
        !           171: }
        !           172:

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