47 lines
1.4 KiB
C
47 lines
1.4 KiB
C
/*=============================================================================
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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) 2010 Fredrik Johansson
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******************************************************************************/
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#include "flint.h"
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#include "ulong_extras.h"
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mp_limb_t n_euler_phi(mp_limb_t n)
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{
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int i;
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mp_limb_t phi;
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n_factor_t fac;
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if (n < 2)
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return n;
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n_factor_init(&fac);
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n_factor(&fac, n, 1);
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phi = UWORD(1);
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for (i = 0; i < fac.num; i++)
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phi *= (fac.p[i]-1) * n_pow(fac.p[i], fac.exp[i]-1);
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return phi;
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}
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