76 lines
2.1 KiB
C
76 lines
2.1 KiB
C
/*=============================================================================
|
|
|
|
This file is part of FLINT.
|
|
|
|
FLINT is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; either version 2 of the License, or
|
|
(at your option) any later version.
|
|
|
|
FLINT is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with FLINT; if not, write to the Free Software
|
|
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
|
|
|
|
=============================================================================*/
|
|
/******************************************************************************
|
|
|
|
Copyright (C) 2012 Fredrik Johansson
|
|
|
|
******************************************************************************/
|
|
|
|
#include "fmpz_mat.h"
|
|
|
|
void
|
|
fmpz_mat_pow(fmpz_mat_t B, const fmpz_mat_t A, ulong exp)
|
|
{
|
|
slong d = fmpz_mat_nrows(A);
|
|
|
|
if (exp <= 2 || d <= 1)
|
|
{
|
|
if (exp == 0 || d == 0)
|
|
{
|
|
fmpz_mat_one(B);
|
|
}
|
|
else if (d == 1)
|
|
{
|
|
fmpz_pow_ui(fmpz_mat_entry(B, 0, 0),
|
|
fmpz_mat_entry(A, 0, 0), exp);
|
|
}
|
|
else if (exp == 1)
|
|
{
|
|
fmpz_mat_set(B, A);
|
|
}
|
|
else if (exp == 2)
|
|
{
|
|
fmpz_mat_sqr(B, A);
|
|
}
|
|
}
|
|
else
|
|
{
|
|
fmpz_mat_t T, U;
|
|
slong i;
|
|
|
|
fmpz_mat_init_set(T, A);
|
|
fmpz_mat_init(U, d, d);
|
|
|
|
for (i = ((slong) FLINT_BIT_COUNT(exp)) - 2; i >= 0; i--)
|
|
{
|
|
fmpz_mat_sqr(U, T);
|
|
|
|
if (exp & (WORD(1) << i))
|
|
fmpz_mat_mul(T, U, A);
|
|
else
|
|
fmpz_mat_swap(T, U);
|
|
}
|
|
|
|
fmpz_mat_swap(B, T);
|
|
fmpz_mat_clear(T);
|
|
fmpz_mat_clear(U);
|
|
}
|
|
}
|