76 lines
2.1 KiB
C
76 lines
2.1 KiB
C
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/*=============================================================================
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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) 2012 Fredrik Johansson
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******************************************************************************/
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#include "fmpz_mat.h"
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void
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fmpz_mat_pow(fmpz_mat_t B, const fmpz_mat_t A, ulong exp)
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{
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slong d = fmpz_mat_nrows(A);
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if (exp <= 2 || d <= 1)
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{
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if (exp == 0 || d == 0)
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{
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fmpz_mat_one(B);
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}
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else if (d == 1)
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{
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fmpz_pow_ui(fmpz_mat_entry(B, 0, 0),
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fmpz_mat_entry(A, 0, 0), exp);
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}
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else if (exp == 1)
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{
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fmpz_mat_set(B, A);
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}
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else if (exp == 2)
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{
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fmpz_mat_sqr(B, A);
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}
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}
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else
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{
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fmpz_mat_t T, U;
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slong i;
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fmpz_mat_init_set(T, A);
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fmpz_mat_init(U, d, d);
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for (i = ((slong) FLINT_BIT_COUNT(exp)) - 2; i >= 0; i--)
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{
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fmpz_mat_sqr(U, T);
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if (exp & (WORD(1) << i))
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fmpz_mat_mul(T, U, A);
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else
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fmpz_mat_swap(T, U);
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}
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fmpz_mat_swap(B, T);
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fmpz_mat_clear(T);
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fmpz_mat_clear(U);
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}
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}
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