mirror of
https://github.com/vale981/arb
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57 lines
1.1 KiB
C
57 lines
1.1 KiB
C
/*
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Copyright (C) 2014 Fredrik Johansson
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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 "mag.h"
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int
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mag_cmp_2exp_si(const mag_t x, slong e)
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{
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int ispow2;
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if (mag_is_special(x))
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{
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if (mag_is_zero(x))
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return -1;
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return 1;
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}
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ispow2 = (MAG_MAN(x) == MAG_ONE_HALF);
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/* Fast path. */
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if (!COEFF_IS_MPZ(MAG_EXP(x)))
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{
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if (ispow2 && (MAG_EXP(x) - 1 == e))
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return 0;
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else
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return (MAG_EXP(x) <= e) ? -1 : 1;
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}
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if (ispow2)
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{
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fmpz_t t;
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fmpz_init(t);
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fmpz_one(t);
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fmpz_add_si(t, t, e);
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if (fmpz_equal(MAG_EXPREF(x), t))
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{
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fmpz_clear(t);
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return 0;
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}
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fmpz_clear(t);
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}
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return (fmpz_cmp_si(MAG_EXPREF(x), e) <= 0) ? -1 : 1;
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}
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