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#include <stdio.h>
#include <math.h>
#include "gmp.h"
#include "gmp-impl.h"
#include "mpfr.h"
#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 i, s, ntotal, p, q, go_on, no, ulps;
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);
TMP_DECL(marker3);
/* 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;
ntotal = ceil(log(p)/log(2)) +1;
no=0;
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==1) {
int err;
err=ceil((3*ntotal+2)*exp(-p*log(2))+3*exp(-p*uo*log(2)/(vo-uo))/log(2));
/* Calculus of un and vn */
for(i=no;i<ntotal;i++) {
mpfr_mul(tmp,u,v,GMP_RNDN);
/* printf("dont la racine est\n"); */
mpfr_sqrt(tmpu,tmp,GMP_RNDN);
/*mpfr_print_raw(tmpu); printf("\n");*/
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);
}
/* printf("avant can_round\n v : "); */
/* mpfr_out_str(stdout,10,0,v,GMP_RNDN); printf("\n u :");
mpfr_out_str(stdout,10,0,u,GMP_RNDN);printf("\n"); */
/* Exactness of the result */
/* Calculus of the nomber of ulps between un and vn */
/*printf("avant sub entre\n");
mpfr_print_raw(v); printf(" -\n");
mpfr_print_raw(u); printf(" , en RNDN\n");*/
mpfr_sub(tmp,v,u,GMP_RNDN);
mpfr_div(tmpu,tmp,u,GMP_RNDN);
mpfr_mul_2exp(tmp,tmpu,q+1,GMP_RNDN);
ulps = (int) floor(mpfr_get_d(tmp));
if (ulps <0) ulps=-ulps;
/* If there is more than 2 ulps, we have to do more iterations
with the same precision */
if( ulps >=2) {
go_on=1;
no=ntotal;
ntotal+=5;
}
/* Else, we could have to work with more precision */
else {
int round1, round2;
mpfr_t res1, res2;
mp_limb_t *res1p, *res2p;
TMP_MARK(marker3);
s=(q-1)/BITS_PER_MP_LIMB+1;
MON_INIT(res1p, res1, q, s);
MON_INIT(res2p, res2, q, s);
round1=mpfr_can_round(v,p-err-1,GMP_RNDU,rnd_mode,q);
round2=mpfr_can_round(u,p-err-1,GMP_RNDD,rnd_mode,q);
mpfr_set(res1, v, rnd_mode);
mpfr_set(res2, u, rnd_mode);
/* If u=v or u & v can be round to the same machine number, we
we have found the correct result */
if (((ulps==0)&&round1)||((ulps==1)&&round1&&round2&&(mpfr_cmp(res1,res2)==0)))
go_on=0;
else {
go_on=1;
p+=5;
no=0;
ntotal+=3;
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);
}
TMP_FREE(marker3);
}
}
/* End of while */
/* Setting of the result */
mpfr_set(r,v,rnd_mode);
/* Let's clean */
TMP_FREE(marker1);
return ;
}
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