1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
|
/* mpfr_agm -- arithmetic-geometric mean of two floating-point numbers
Copyright (C) 1999 PolKA project, Inria Lorraine and Loria
This file is part of the MPFR Library.
The MPFR Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Library General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at your
option) any later version.
The MPFR Library 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 Library General Public
License for more details.
You should have received a copy of the GNU Library General Public License
along with the MPFR Library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */
#include <stdio.h>
#include <math.h>
#include "gmp.h"
#include "gmp-impl.h"
#include "mpfr.h"
/*Memory gestion */
#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;
void
#ifdef __STDC__
mpfr_agm(mpfr_ptr r, mpfr_srcptr op2, mpfr_srcptr op1, unsigned char rnd_mode)
#else
mpfr_agm(r, a, b, rnd_mode)
mpfr_ptr r;
mpfr_srcptr a;
mpfr_srcptr b;
unsigned char rnd_mode;
#endif
{
int s, p, q, go_on;
double uo, vo;
mp_limb_t *up, *vp, *tmpp, *tmpup, *tmpvp, *ap, *bp;
mpfr_t u, v, tmp, tmpu, tmpv, a, b;
TMP_DECL(marker1);
TMP_DECL(marker2);
/* If a or b is NaN, the result is NaN */
if (FLAG_NAN(op1) || FLAG_NAN(op2))
{ SET_NAN(r); return; }
/* If a or b is negative, the result is NaN */
if ((SIGN(op1)<0)||(SIGN(op2)<0))
{ SET_NAN(r); return; }
/* If a or b is 0, the result is 0 */
if ((SIGN(op1)==0)||(SIGN(op2)==0))
{ SET_ZERO(r);
return;
}
/* precision of the following calculus */
q = PREC(r);
p = q + 15;
/* Initialisations */
go_on=1;
TMP_MARK(marker1);
s=(p-1)/BITS_PER_MP_LIMB+1;
MON_INIT(ap, a, p, s);
MON_INIT(bp, b, p, s);
TMP_MARK(marker2);
MON_INIT(up, u, p, s);
MON_INIT(vp, v, p, s);
MON_INIT(tmpup, tmpu, p, s);
MON_INIT(tmpvp, tmpv, p, s);
MON_INIT(tmpp, tmp, p, s);
/* b and a will be the 2 operands but I want b>= a */
if (mpfr_cmp(op1,op2) > 0) {
mpfr_set(b,op1,GMP_RNDN); mpfr_set(a,op2,GMP_RNDN);
}
else {
mpfr_set(b,op2,GMP_RNDN); mpfr_set(a,op1,GMP_RNDN);
}
vo=mpfr_get_d(b);
uo=mpfr_get_d(a);
mpfr_set(u,a,GMP_RNDN);
mpfr_set(v,b,GMP_RNDN);
/* Main loop */
while (go_on) {
int err, eq, can_round;
eq=0;
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)));
if(p-err-3<=q) {
p=q+err+4;
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)));
}
/* Calculus of un and vn */
while (eq<=p-2) {
mpfr_mul(tmp,u,v,GMP_RNDN);
mpfr_sqrt3(tmpu,tmp,GMP_RNDN);
mpfr_add(tmp,u,v,GMP_RNDN);
mpfr_div_2exp(tmpv,tmp,1,GMP_RNDN);
mpfr_set(u,tmpu,GMP_RNDN);
mpfr_set(v,tmpv,GMP_RNDN);
if (mpfr_cmp(v,u)>=0)
eq=mpfr_cmp2(v,u);
else
eq=mpfr_cmp2(u,v);
}
/* printf("avant can_round %i bits faux\n v : ",err+3);
mpfr_print_raw(v); printf("\n u : ");
mpfr_print_raw(u);printf("\n");*/
/* Roundability of the result */
can_round=mpfr_can_round(v,p-err-3,GMP_RNDN,rnd_mode,q);
if (can_round)
go_on=0;
else {
go_on=1;
p+=5;
TMP_FREE(marker2);
TMP_MARK(marker2);
s=(p-1)/BITS_PER_MP_LIMB+1;
MON_INIT(up, u, p, s);
MON_INIT(vp, v, p, s);
MON_INIT(tmpup, tmpu, p, s);
MON_INIT(tmpvp, tmpv, p, s);
MON_INIT(tmpp, tmp, p, s);
mpfr_set(u,a,GMP_RNDN);
mpfr_set(v,b,GMP_RNDN);
}
}
/* End of while */
/* Setting of the result */
mpfr_set(r,v,rnd_mode);
/* Let's clean */
TMP_FREE(marker1);
return ;
}
|
