/* y=0 is not permitted if x<=0. No error messages are given. */
void __mpatan2(mp_no *y, mp_no *x, mp_no *z, int p) {
static const double ZERO = 0.0, ONE = 1.0;
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}};
mp_no mpt1,mpt2,mpt3;
if (X[0] <= ZERO) {
mpone.e = 1; mpone.d[0] = mpone.d[1] = ONE;
__dvd(x,y,&mpt1,p); __mul(&mpt1,&mpt1,&mpt2,p);
if (mpt1.d[0] != ZERO) mpt1.d[0] = ONE;
__add(&mpt2,&mpone,&mpt3,p); __mpsqrt(&mpt3,&mpt2,p);
__add(&mpt1,&mpt2,&mpt3,p); mpt3.d[0]=Y[0];
__mpatan(&mpt3,&mpt1,p); __add(&mpt1,&mpt1,z,p);
}
else
{ __dvd(y,x,&mpt1,p);
__mpatan(&mpt1,z,p);
}
return;
}
/* Final stages. Compute atan(x) by multiple precision arithmetic */
static double
atanMp (double x, const int pr[])
{
mp_no mpx, mpy, mpy2, mperr, mpt1, mpy1;
double y1, y2;
int i, p;
for (i = 0; i < M; i++)
{
p = pr[i];
__dbl_mp (x, &mpx, p);
__mpatan (&mpx, &mpy, p);
__dbl_mp (u9[i].d, &mpt1, p);
__mul (&mpy, &mpt1, &mperr, p);
__add (&mpy, &mperr, &mpy1, p);
__sub (&mpy, &mperr, &mpy2, p);
__mp_dbl (&mpy1, &y1, p);
__mp_dbl (&mpy2, &y2, p);
if (y1 == y2)
{
LIBC_PROBE (slowatan, 3, &p, &x, &y1);
return y1;
}
}
LIBC_PROBE (slowatan_inexact, 3, &p, &x, &y1);
return y1; /*if impossible to do exact computing */
}