1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
/*
Copyright (C) 2010 William Hart
Copyright (C) 2010, 2012 Sebastian Pancratz
Copyright (C) 2023 Fredrik Johansson
This file is part of FLINT.
FLINT is free software: you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License (LGPL) as published
by the Free Software Foundation; either version 3 of the License, or
(at your option) any later version. See <https://www.gnu.org/licenses/>.
*/
#include "nmod_poly.h"
#include "gr_poly.h"
void
_nmod_poly_compose(nn_ptr res, nn_srcptr poly1, slong len1,
nn_srcptr poly2, slong len2, nmod_t mod)
{
if (len1 == 1)
res[0] = poly1[0];
else if (len2 == 1)
res[0] = _nmod_poly_evaluate_nmod(poly1, len1, poly2[0], mod);
else if (len1 <= 7)
_nmod_poly_compose_horner(res, poly1, len1, poly2, len2, mod);
else
{
/* delegates to Taylor shift, divconquer */
/* todo: also incorporate the nmod_poly Taylor shift in gr_poly */
gr_ctx_t ctx;
_gr_ctx_init_nmod(ctx, &mod);
GR_MUST_SUCCEED(_gr_poly_compose(res, poly1, len1, poly2, len2, ctx));
}
}
void nmod_poly_compose(nmod_poly_t res,
const nmod_poly_t poly1, const nmod_poly_t poly2)
{
const slong len1 = poly1->length;
const slong len2 = poly2->length;
if (len1 == 0)
{
nmod_poly_zero(res);
}
else if (len1 == 1 || len2 == 0)
{
nmod_poly_fit_length(res, 1);
res->coeffs[0] = poly1->coeffs[0];
res->length = (res->coeffs[0] != 0);
}
else
{
const slong lenr = (len1 - 1) * (len2 - 1) + 1;
if (res != poly1 && res != poly2)
{
nmod_poly_fit_length(res, lenr);
_nmod_poly_compose(res->coeffs, poly1->coeffs, len1,
poly2->coeffs, len2, poly1->mod);
}
else
{
nmod_poly_t t;
nmod_poly_init2(t, poly1->mod.n, lenr);
_nmod_poly_compose(t->coeffs, poly1->coeffs, len1,
poly2->coeffs, len2, poly1->mod);
nmod_poly_swap(res, t);
nmod_poly_clear(t);
}
res->length = lenr;
_nmod_poly_normalise(res);
}
}