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https://github.com/vale981/arb
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6bf072eb59
This will allow us to not loose the julia session on error. See also https://github.com/wbhart/flint2/pull/243
47 lines
1.1 KiB
C
47 lines
1.1 KiB
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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ulong
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dlog_mod2e_1mod4(ulong b1, ulong e, ulong inv5, nmod_t pe)
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{
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slong f;
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ulong pf1, pf, x, xf;
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pf1 = 1;
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pf = 4;
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x = 0;
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for (f = 2; f < e; f++)
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{
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if (b1 % pf != 1)
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{
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flint_printf("ERROR dlog_mod2e: %wu %% %wu != 1 mod %wu\n\n",
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b1, pf, pe.n);
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flint_abort();
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}
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xf = (b1 - 1) / pf;
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xf = (f == 2) ? xf % 4 : (xf % 2) * (pf1 / 2);
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b1 = nmod_mul(b1, nmod_pow_ui(inv5, xf, pe), pe);
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x += xf;
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pf1 = pf;
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pf *= 2;
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}
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return x;
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}
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ulong
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dlog_mod2e(const dlog_modpe_t t, ulong b1)
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{
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if (t->e == 2)
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return (b1 % 4) == 3;
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else
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return dlog_mod2e_1mod4(b1, t->e, t->inva, t->pe);
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}
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