void
acb_poly_mul(acb_poly_t res, const acb_poly_t poly1,
const acb_poly_t poly2, slong prec)
{
slong len_out;
if ((poly1->length == 0) || (poly2->length == 0))
{
acb_poly_zero(res);
return;
}
len_out = poly1->length + poly2->length - 1;
if (res == poly1 || res == poly2)
{
acb_poly_t temp;
acb_poly_init2(temp, len_out);
_acb_poly_mul(temp->coeffs, poly1->coeffs, poly1->length,
poly2->coeffs, poly2->length, prec);
acb_poly_swap(res, temp);
acb_poly_clear(temp);
}
else
{
acb_poly_fit_length(res, len_out);
_acb_poly_mul(res->coeffs, poly1->coeffs, poly1->length,
poly2->coeffs, poly2->length, prec);
}
_acb_poly_set_length(res, len_out);
_acb_poly_normalise(res);
}
void
_acb_poly_interpolate_fast_precomp(acb_ptr poly,
acb_srcptr ys, acb_ptr * tree, acb_srcptr weights,
slong len, slong prec)
{
acb_ptr t, u, pa, pb;
slong i, pow, left;
if (len == 0)
return;
t = _acb_vec_init(len);
u = _acb_vec_init(len);
for (i = 0; i < len; i++)
acb_mul(poly + i, weights + i, ys + i, prec);
for (i = 0; i < FLINT_CLOG2(len); i++)
{
pow = (WORD(1) << i);
pa = tree[i];
pb = poly;
left = len;
while (left >= 2 * pow)
{
_acb_poly_mul(t, pa, pow + 1, pb + pow, pow, prec);
_acb_poly_mul(u, pa + pow + 1, pow + 1, pb, pow, prec);
_acb_vec_add(pb, t, u, 2 * pow, prec);
left -= 2 * pow;
pa += 2 * pow + 2;
pb += 2 * pow;
}
if (left > pow)
{
_acb_poly_mul(t, pa, pow + 1, pb + pow, left - pow, prec);
_acb_poly_mul(u, pb, pow, pa + pow + 1, left - pow + 1, prec);
_acb_vec_add(pb, t, u, left, prec);
}
}
_acb_vec_clear(t, len);
_acb_vec_clear(u, len);
}
void
_acb_poly_compose_series_horner(acb_ptr res, acb_srcptr poly1, slong len1,
acb_srcptr poly2, slong len2, slong n, slong prec)
{
if (n == 1)
{
acb_set(res, poly1);
}
else
{
slong i = len1 - 1;
slong lenr;
acb_ptr t = _acb_vec_init(n);
lenr = len2;
_acb_vec_scalar_mul(res, poly2, len2, poly1 + i, prec);
i--;
acb_add(res, res, poly1 + i, prec);
while (i > 0)
{
i--;
if (lenr + len2 - 1 < n)
{
_acb_poly_mul(t, res, lenr, poly2, len2, prec);
lenr = lenr + len2 - 1;
}
else
{
_acb_poly_mullow(t, res, lenr, poly2, len2, n, prec);
lenr = n;
}
_acb_poly_add(res, t, lenr, poly1 + i, 1, prec);
}
_acb_vec_zero(res + lenr, n - lenr);
_acb_vec_clear(t, n);
}
}
