1 /*
2 Copyright (C) 2010 Sebastian Pancratz
3 Copyright (C) 2014 Fredrik Johansson
4 Copyright (C) 2019 William Hart
5
6 This file is part of FLINT.
7
8 FLINT is free software: you can redistribute it and/or modify it under
9 the terms of the GNU Lesser General Public License (LGPL) as published
10 by the Free Software Foundation; either version 2.1 of the License, or
11 (at your option) any later version. See <http://www.gnu.org/licenses/>.
12 */
13
14 #include "fmpz_poly.h"
15
16 void
_fmpz_poly_div_series(fmpz * Q,const fmpz * A,slong Alen,const fmpz * B,slong Blen,slong n)17 _fmpz_poly_div_series(fmpz * Q, const fmpz * A, slong Alen,
18 const fmpz * B, slong Blen, slong n)
19 {
20 Alen = FLINT_MIN(Alen, n);
21 Blen = FLINT_MIN(Blen, n);
22
23 if (n < 32 || Blen < 20)
24 _fmpz_poly_div_series_basecase(Q, A, Alen, B, Blen, n);
25 else if (fmpz_is_pm1(B + 0))
26 {
27 fmpz * Binv = _fmpz_vec_init(n);
28
29 _fmpz_poly_inv_series(Binv, B, Blen, n);
30 _fmpz_poly_mullow(Q, Binv, n, A, Alen, n);
31
32 _fmpz_vec_clear(Binv, n);
33 } else
34 _fmpz_poly_div_series_divconquer(Q, A, Alen, B, Blen, n);
35 }
36
fmpz_poly_div_series(fmpz_poly_t Q,const fmpz_poly_t A,const fmpz_poly_t B,slong n)37 void fmpz_poly_div_series(fmpz_poly_t Q, const fmpz_poly_t A,
38 const fmpz_poly_t B, slong n)
39 {
40 slong Alen = FLINT_MIN(A->length, n);
41 slong Blen = FLINT_MIN(B->length, n);
42
43 if (Blen == 0)
44 {
45 flint_printf("Exception (fmpz_poly_div_series). Division by zero.\n");
46 flint_abort();
47 }
48
49 if (Alen == 0)
50 {
51 fmpz_poly_zero(Q);
52 return;
53 }
54
55 if (Q == A || Q == B)
56 {
57 fmpz_poly_t t;
58 fmpz_poly_init2(t, n);
59 _fmpz_poly_div_series(t->coeffs, A->coeffs, Alen, B->coeffs, Blen, n);
60 fmpz_poly_swap(Q, t);
61 fmpz_poly_clear(t);
62 }
63 else
64 {
65 fmpz_poly_fit_length(Q, n);
66 _fmpz_poly_div_series(Q->coeffs, A->coeffs, Alen, B->coeffs, Blen, n);
67 }
68
69 _fmpz_poly_set_length(Q, n);
70 _fmpz_poly_normalise(Q);
71 }
72