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/*
Copyright (C) 2012 Fredrik Johansson
This file is part of Arb.
Arb 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 2.1 of the License, or
(at your option) any later version. See <http://www.gnu.org/licenses/>.
*/
#include "acb_mat.h"
void
acb_mat_pow_ui(acb_mat_t B, const acb_mat_t A, ulong exp, slong prec)
{
slong d = acb_mat_nrows(A);
if (exp <= 2 || d <= 1)
{
if (exp == 0 || d == 0)
{
acb_mat_one(B);
}
else if (d == 1)
{
acb_pow_ui(acb_mat_entry(B, 0, 0),
acb_mat_entry(A, 0, 0), exp, prec);
}
else if (exp == 1)
{
acb_mat_set(B, A);
}
else if (exp == 2)
{
acb_mat_sqr(B, A, prec);
}
}
else
{
acb_mat_t T, U;
slong i;
acb_mat_init(T, d, d);
acb_mat_set(T, A);
acb_mat_init(U, d, d);
for (i = ((slong) FLINT_BIT_COUNT(exp)) - 2; i >= 0; i--)
{
acb_mat_sqr(U, T, prec);
if (exp & (WORD(1) << i))
acb_mat_mul(T, U, A, prec);
else
acb_mat_swap(T, U);
}
acb_mat_swap(B, T);
acb_mat_clear(T);
acb_mat_clear(U);
}
}
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