flint-sys 0.9.0

Bindings to the FLINT C library
Documentation 
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
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95

/*
    Copyright (C) 2011 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_vec.h"
#include "nmod_poly.h"

void _nmod_poly_mulmod(nn_ptr res, nn_srcptr poly1, slong len1,
                             nn_srcptr poly2, slong len2, nn_srcptr f,
                            slong lenf, nmod_t mod)
{
    nn_ptr T, Q;
    slong lenT, lenQ;
    TMP_INIT;

    if (lenf == 2 && len1 == 1 && len2 == 1)
    {
        res[0] = nmod_mul(poly1[0], poly2[0], mod);
        return;
    }

    lenT = len1 + len2 - 1;
    lenQ = lenT - lenf + 1;

    FLINT_ASSERT(lenQ >= 1);

    TMP_START;
    T = TMP_ALLOC(sizeof(ulong) * (lenT + lenQ));
    Q = T + lenT;

    if (len1 >= len2)
        _nmod_poly_mul(T, poly1, len1, poly2, len2, mod);
    else
        _nmod_poly_mul(T, poly2, len2, poly1, len1, mod);

    _nmod_poly_divrem(Q, res, T, lenT, f, lenf, mod);

    TMP_END;
}

void
nmod_poly_mulmod(nmod_poly_t res,
    const nmod_poly_t poly1, const nmod_poly_t poly2, const nmod_poly_t f)
{
    slong len1, len2, lenf;
    nn_ptr fcoeffs;

    lenf = f->length;
    len1 = poly1->length;
    len2 = poly2->length;

    if (lenf == 0)
    {
        flint_throw(FLINT_ERROR, "Exception (nmod_poly_mulmod). Divide by zero.\n");
    }

    if (lenf == 1 || len1 == 0 || len2 == 0)
    {
        nmod_poly_zero(res);
        return;
    }

    if (len1 + len2 - lenf > 0)
    {
        if (f == res)
        {
            fcoeffs = flint_malloc(sizeof(ulong) * lenf);
            _nmod_vec_set(fcoeffs, f->coeffs, lenf);
        }
        else
            fcoeffs = f->coeffs;

        nmod_poly_fit_length(res, lenf - 1);
        _nmod_poly_mulmod(res->coeffs, poly1->coeffs, len1,
                                       poly2->coeffs, len2,
                                       fcoeffs, lenf,
                                       res->mod);
        if (f == res)
            flint_free(fcoeffs);

        res->length = lenf - 1;
        _nmod_poly_normalise(res);
    }
    else
    {
        nmod_poly_mul(res, poly1, poly2);
    }
}