68 lines
1.9 KiB
C
68 lines
1.9 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) 2010 Fredrik Johansson
|
|
|
|
******************************************************************************/
|
|
|
|
#include "fmpz.h"
|
|
#include "arith.h"
|
|
|
|
void arith_euler_phi(fmpz_t res, const fmpz_t n)
|
|
{
|
|
fmpz_factor_t factors;
|
|
fmpz_t t;
|
|
ulong exp;
|
|
slong i;
|
|
|
|
if (fmpz_sgn(n) <= 0)
|
|
{
|
|
fmpz_zero(res);
|
|
return;
|
|
}
|
|
|
|
if (fmpz_abs_fits_ui(n))
|
|
{
|
|
fmpz_set_ui(res, n_euler_phi(fmpz_get_ui(n)));
|
|
return;
|
|
}
|
|
|
|
fmpz_factor_init(factors);
|
|
fmpz_factor(factors, n);
|
|
fmpz_one(res);
|
|
|
|
fmpz_init(t);
|
|
for (i = 0; i < factors->num; i++)
|
|
{
|
|
fmpz_sub_ui(t, factors->p + i, UWORD(1));
|
|
fmpz_mul(res, res, t);
|
|
exp = factors->exp[i];
|
|
if (exp != 1)
|
|
{
|
|
fmpz_pow_ui(t, factors->p + i, exp - UWORD(1));
|
|
fmpz_mul(res, res, t);
|
|
}
|
|
}
|
|
|
|
fmpz_clear(t);
|
|
fmpz_factor_clear(factors);
|
|
}
|