256 lines
7.0 KiB
C
256 lines
7.0 KiB
C
/*=============================================================================
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This file is part of FLINT.
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FLINT is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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FLINT is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with FLINT; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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=============================================================================*/
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/******************************************************************************
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Copyright (C) 2011 Fredrik Johansson
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Copyright (C) 2012 Lina Kulakova
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Copyright (C) 2013 Martin Lee
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******************************************************************************/
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#include <gmp.h>
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#include "flint.h"
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#include "fmpz_vec.h"
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#include "fmpz_mod_poly.h"
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#include "fmpz_mat.h"
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#include "ulong_extras.h"
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void
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_fmpz_mod_poly_reduce_matrix_mod_poly (fmpz_mat_t A, const fmpz_mat_t B,
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const fmpz_mod_poly_t f)
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{
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fmpz * tmp1, *tmp2;
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slong n = f->length - 1;
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slong i, m = n_sqrt(n) + 1;
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fmpz_t invf;
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fmpz_init(invf);
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fmpz_invmod(invf, f->coeffs + n, &f->p);
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fmpz_mat_init(A, m, n);
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fmpz_one(A->rows[0]);
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tmp1 = _fmpz_vec_init(2 * (B->c) - n);
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tmp2 = tmp1 + (B->c - n);
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for (i= 1; i < m; i++)
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{
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_fmpz_mod_poly_divrem(tmp1, tmp2, B->rows[i], B->c, f->coeffs,
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f->length, invf, &f->p);
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_fmpz_vec_set(A->rows[i], tmp2, n);
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}
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_fmpz_vec_clear(tmp1, 2 * (B->c) - n);
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fmpz_clear(invf);
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}
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void
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_fmpz_mod_poly_precompute_matrix (fmpz_mat_t A, const fmpz * poly1,
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const fmpz * poly2, slong len2, const fmpz * poly2inv,
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slong len2inv, const fmpz_t p)
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{
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/* Set rows of A to powers of poly1 */
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slong i, n, m;
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n = len2 - 1;
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m = n_sqrt(n) + 1;
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fmpz_one(A->rows[0]);
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_fmpz_vec_set(A->rows[1], poly1, n);
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for (i = 2; i < m; i++)
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_fmpz_mod_poly_mulmod_preinv(A->rows[i], A->rows[i - 1], n, poly1, n,
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poly2, len2, poly2inv, len2inv, p);
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}
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void
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fmpz_mod_poly_precompute_matrix(fmpz_mat_t A, const fmpz_mod_poly_t poly1,
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const fmpz_mod_poly_t poly2, const fmpz_mod_poly_t poly2inv)
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{
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slong len1 = poly1->length;
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slong len2 = poly2->length;
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slong len = len2 - 1;
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slong vec_len = FLINT_MAX(len2 - 1, len1);
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slong m= n_sqrt(len) + 1;
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fmpz* ptr;
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fmpz_t inv2;
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if (len2 == 0)
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{
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flint_printf("Exception (fmpz_mod_poly_precompute_matrix)."
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"Division by zero.\n");
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abort();
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}
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if (A->r != m || A->c != len)
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{
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flint_printf("Exception (fmpz_mod_poly_precompute_matrix)."
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" Wrong dimensions.\n");
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abort();
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}
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if (len2 == 1)
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{
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fmpz_mat_zero(A);
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return;
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}
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ptr = _fmpz_vec_init(vec_len);
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if (len1 <= len)
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{
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_fmpz_vec_set(ptr, poly1->coeffs, len1);
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_fmpz_vec_zero(ptr + len1, vec_len - len1);
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}
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else
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{
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fmpz_init(inv2);
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fmpz_invmod(inv2, poly2->coeffs + len, &poly1->p);
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_fmpz_mod_poly_rem(ptr, poly1->coeffs, len1,
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poly2->coeffs, len2, inv2, &poly1->p);
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fmpz_clear(inv2);
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}
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_fmpz_mod_poly_precompute_matrix (A, ptr, poly2->coeffs, len2,
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poly2inv->coeffs, poly2inv->length, &poly1->p);
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_fmpz_vec_clear(ptr, vec_len);
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}
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void
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_fmpz_mod_poly_compose_mod_brent_kung_precomp_preinv(fmpz * res,
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const fmpz * poly1, slong len1, const fmpz_mat_t A, const fmpz * poly3,
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slong len3, const fmpz * poly3inv, slong len3inv, const fmpz_t p)
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{
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fmpz_mat_t B, C;
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fmpz * t, * h;
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slong i, j, n, m;
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n = len3 - 1;
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if (len3 == 1)
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return;
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if (len1 == 1)
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{
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fmpz_set(res, poly1);
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return;
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}
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if (len3 == 2)
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{
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_fmpz_mod_poly_evaluate_fmpz(res, poly1, len1, A->rows[1], p);
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return;
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}
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m = n_sqrt(n) + 1;
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fmpz_mat_init(B, m, m);
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fmpz_mat_init(C, m, n);
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h = _fmpz_vec_init(n);
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t = _fmpz_vec_init(n);
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/* Set rows of B to the segments of poly1 */
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for (i = 0; i < len1 / m; i++)
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_fmpz_vec_set(B->rows[i], poly1 + i * m, m);
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_fmpz_vec_set(B->rows[i], poly1 + i * m, len1 % m);
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fmpz_mat_mul(C, B, A);
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for (i = 0; i < m; i++)
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for (j = 0; j < n; j++)
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fmpz_mod(C->rows[i] + j, C->rows[i] + j, p);
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/* Evaluate block composition using the Horner scheme */
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_fmpz_vec_set(res, C->rows[m - 1], n);
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_fmpz_mod_poly_mulmod_preinv(h, A->rows[m - 1], n, A->rows[1], n, poly3,
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len3, poly3inv, len3inv, p);
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for (i = m - 2; i >= 0; i--)
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{
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_fmpz_mod_poly_mulmod_preinv(t, res, n, h, n, poly3, len3,
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poly3inv, len3inv, p);
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_fmpz_mod_poly_add(res, t, n, C->rows[i], n, p);
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}
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_fmpz_vec_clear(h, n);
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_fmpz_vec_clear(t, n);
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fmpz_mat_clear(B);
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fmpz_mat_clear(C);
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}
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void
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fmpz_mod_poly_compose_mod_brent_kung_precomp_preinv(fmpz_mod_poly_t res,
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const fmpz_mod_poly_t poly1, const fmpz_mat_t A,
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const fmpz_mod_poly_t poly3, const fmpz_mod_poly_t poly3inv)
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{
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slong len1 = poly1->length;
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slong len3 = poly3->length;
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slong len = len3 - 1;
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if (len3 == 0)
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{
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flint_printf("Exception (fmpz_mod_poly_compose_mod_brent_kung_precomp_preinv)."
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"Division by zero\n");
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abort();
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}
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if (len1 >= len3)
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{
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flint_printf("Exception (fmpz_mod_poly_compose_mod_brent_kung_precomp_preinv)."
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"The degree of the first polynomial must be smaller than that of the "
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" modulus\n");
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abort();
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}
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if (len1 == 0 || len3 == 1)
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{
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fmpz_mod_poly_zero(res);
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return;
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}
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if (len1 == 1)
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{
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fmpz_mod_poly_set(res, poly1);
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return;
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}
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if (res == poly3 || res == poly1 || res == poly3inv)
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{
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fmpz_mod_poly_t tmp;
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fmpz_mod_poly_init(tmp, &res->p);
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fmpz_mod_poly_compose_mod_brent_kung_precomp_preinv(tmp, poly1, A,
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poly3, poly3inv);
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fmpz_mod_poly_swap(tmp, res);
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fmpz_mod_poly_clear(tmp);
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return;
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}
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fmpz_mod_poly_fit_length(res, len);
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_fmpz_mod_poly_compose_mod_brent_kung_precomp_preinv(res->coeffs,
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poly1->coeffs, len1, A, poly3->coeffs, len3,
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poly3inv->coeffs, poly3inv->length, &res->p);
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_fmpz_mod_poly_set_length(res, len);
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_fmpz_mod_poly_normalise(res);
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}
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