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https://github.com/vale981/arb
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48 lines
1.4 KiB
C
48 lines
1.4 KiB
C
/*
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Copyright (C) 2012 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 "fmpr.h"
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slong _fmpr_add_eps(fmpr_t z, const fmpr_t x, int sign, slong prec, fmpr_rnd_t rnd)
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{
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slong bits, shift;
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int xsign;
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xsign = fmpz_sgn(fmpr_manref(x));
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if ((rnd == FMPR_RND_DOWN && xsign != sign) ||
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(rnd == FMPR_RND_UP && xsign == sign) ||
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(rnd == FMPR_RND_FLOOR && sign < 0) ||
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(rnd == FMPR_RND_CEIL && sign > 0))
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{
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bits = fmpz_bits(fmpr_manref(x));
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shift = 2 + FLINT_MAX(0, prec - bits);
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fmpz_mul_2exp(fmpr_manref(z), fmpr_manref(x), shift);
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fmpz_sub_ui(fmpr_expref(z), fmpr_expref(x), shift);
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if (sign > 0)
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fmpz_add_ui(fmpr_manref(z), fmpr_manref(z), 1);
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else
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fmpz_sub_ui(fmpr_manref(z), fmpr_manref(z), 1);
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return _fmpr_normalise(fmpr_manref(z), fmpr_expref(z), prec, rnd);
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}
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else
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{
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slong ret = fmpr_set_round(z, x, prec, rnd);
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if (ret == FMPR_RESULT_EXACT)
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return prec - fmpz_bits(fmpr_manref(z));
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else
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return ret;
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}
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}
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