void fmpz_poly_compose_divconquer(fmpz_poly_t res, const fmpz_poly_t poly1, const fmpz_poly_t poly2) { const long len1 = poly1->length; const long len2 = poly2->length; long 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_divconquer(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_divconquer(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); } }
void _fmpz_poly_compose(fmpz * res, const fmpz * poly1, slong len1, const fmpz * poly2, slong len2) { if (len1 == 1) fmpz_set(res, poly1); else if (len2 == 1) _fmpz_poly_evaluate_fmpz(res, poly1, len1, poly2); else if (len1 <= 4) _fmpz_poly_compose_horner(res, poly1, len1, poly2, len2); else _fmpz_poly_compose_divconquer(res, poly1, len1, poly2, len2); }