void
_fmpq_poly_compose(fmpz * res, fmpz_t den, const fmpz * poly1, const fmpz_t den1,
long len1, const fmpz * poly2, const fmpz_t den2, long len2)
{
if (*den2 == 1L)
{
_fmpz_poly_compose(res, poly1, len1, poly2, len2);
fmpz_set(den, den1);
_fmpq_poly_canonicalise(res, den, (len1 - 1L) * (len2 - 1L) + 1L);
}
else
{
fmpz_t one;
fmpz * v = _fmpz_vec_init(len1);
fmpz_init(one);
fmpz_one(one);
_fmpq_poly_rescale(v, den, poly1, den1, len1, one, den2);
_fmpz_poly_compose(res, v, len1, poly2, len2);
_fmpq_poly_canonicalise(res, den, (len1 - 1L) * (len2 - 1L) + 1L);
fmpz_clear(one);
_fmpz_vec_clear(v, len1);
}
}
void
fmpz_poly_compose(fmpz_poly_t res,
const fmpz_poly_t poly1, const fmpz_poly_t poly2)
{
const slong len1 = poly1->length;
const slong len2 = poly2->length;
slong lenr;
if (len1 == 0)
{
fmpz_poly_zero(res);
return;
}
if (len1 == 1 || len2 == 0)
{
fmpz_poly_set_fmpz(res, poly1->coeffs);
return;
}
lenr = (len1 - 1) * (len2 - 1) + 1;
if (res != poly1 && res != poly2)
{
fmpz_poly_fit_length(res, lenr);
_fmpz_poly_compose(res->coeffs, poly1->coeffs, len1,
poly2->coeffs, len2);
_fmpz_poly_set_length(res, lenr);
_fmpz_poly_normalise(res);
}
else
{
fmpz_poly_t t;
fmpz_poly_init2(t, lenr);
_fmpz_poly_compose(t->coeffs, poly1->coeffs, len1,
poly2->coeffs, len2);
_fmpz_poly_set_length(t, lenr);
_fmpz_poly_normalise(t);
fmpz_poly_swap(res, t);
fmpz_poly_clear(t);
}
}