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https://github.com/vale981/arb
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32 lines
863 B
C
32 lines
863 B
C
/*
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Copyright (C) 2016 Pascal Molin
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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 it under
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the terms of the GNU Lesser General Public License (LGPL) as published
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by the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version. See <http://www.gnu.org/licenses/>.
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*/
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#include "dlog.h"
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void
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dlog_1modpe_init(dlog_1modpe_t t, ulong a1, ulong p, ulong e, nmod_t pe)
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{
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if (e == 1)
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{
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t->inv1p = 1;
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t->invloga1 = 0;
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}
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else
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{
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ulong loga1;
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if (a1 == 1)
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abort();
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t->inv1p = nmod_inv(1 + p, pe); /* 1 - p + p^2 - ... */
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loga1 = dlog_1modpe_1modp(a1, p, e, t->inv1p, pe);
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/* only need inverse mod p^(e-1) but does not hurt */
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t->invloga1 = nmod_inv(loga1, pe);
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}
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}
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