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https://github.com/vale981/arb
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77 lines
2.1 KiB
C
77 lines
2.1 KiB
C
/*=============================================================================
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This file is part of ARB.
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ARB 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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ARB 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 ARB; 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 "arb_mat.h"
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void
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arb_mat_pow_ui(arb_mat_t B, const arb_mat_t A, ulong exp, long prec)
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{
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long d = arb_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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arb_mat_one(B);
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}
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else if (d == 1)
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{
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arb_pow_ui(arb_mat_entry(B, 0, 0),
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arb_mat_entry(A, 0, 0), exp, prec);
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}
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else if (exp == 1)
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{
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arb_mat_set(B, A);
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}
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else if (exp == 2)
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{
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arb_mat_mul(B, A, A, prec); /* todo: sqr */
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}
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}
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else
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{
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arb_mat_t T, U;
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long i;
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arb_mat_init(T, d, d);
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arb_mat_set(T, A);
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arb_mat_init(U, d, d);
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for (i = ((long) FLINT_BIT_COUNT(exp)) - 2; i >= 0; i--)
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{
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arb_mat_mul(U, T, T, prec); /* todo: sqr */
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if (exp & (1L << i))
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arb_mat_mul(T, U, A, prec);
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else
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arb_mat_swap(T, U);
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}
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arb_mat_swap(B, T);
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arb_mat_clear(T);
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arb_mat_clear(U);
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}
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}
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