mirror of
https://github.com/vale981/arb
synced 2025-03-05 09:21:38 -05:00
69 lines
1.5 KiB
C
69 lines
1.5 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
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fmpr_rsqrt(fmpr_t y, const fmpr_t x, slong prec, fmpr_rnd_t rnd)
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{
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slong r;
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if (fmpr_is_special(x))
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{
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if (fmpr_is_zero(x))
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fmpr_pos_inf(y);
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else if (fmpr_is_pos_inf(x))
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fmpr_zero(y);
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else
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fmpr_nan(y);
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return FMPR_RESULT_EXACT;
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}
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if (fmpr_sgn(x) < 0)
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{
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fmpr_nan(y);
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return FMPR_RESULT_EXACT;
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}
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/* special case: 4^n */
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if (fmpz_is_one(fmpr_manref(x)) && fmpz_is_even(fmpr_expref(x)))
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{
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r = fmpr_set_round(y, x, prec, rnd);
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fmpz_tdiv_q_2exp(fmpr_expref(y), fmpr_expref(y), 1);
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fmpz_neg(fmpr_expref(y), fmpr_expref(y));
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return r;
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}
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{
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fmpr_t t;
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fmpz_t e;
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fmpr_init(t);
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fmpz_init(e);
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fmpz_neg(e, fmpr_expref(x));
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if (fmpz_is_odd(e))
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fmpz_add_ui(e, e, 1);
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fmpr_mul_2exp_fmpz(t, x, e);
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CALL_MPFR_FUNC(r, mpfr_rec_sqrt, y, t, prec, rnd);
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fmpz_tdiv_q_2exp(e, e, 1);
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fmpr_mul_2exp_fmpz(y, y, e);
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fmpr_clear(t);
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fmpz_clear(e);
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return r;
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}
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}
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