mirror of
https://github.com/vale981/arb
synced 2025-03-05 09:21:38 -05:00
91 lines
1.9 KiB
C
91 lines
1.9 KiB
C
/*
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Copyright (C) 2015 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 "arf.h"
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int
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arf_root(arf_ptr z, arf_srcptr x, ulong k, slong prec, arf_rnd_t rnd)
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{
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mp_size_t xn, zn, val;
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mp_srcptr xptr;
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mp_ptr tmp, zptr;
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mpfr_t xf, zf;
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fmpz_t q, r;
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int inexact;
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if (k == 0)
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{
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arf_nan(z);
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return 0;
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}
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if (k == 1)
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return arf_set_round(z, x, prec, rnd);
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if (k == 2)
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return arf_sqrt(z, x, prec, rnd);
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if (arf_is_special(x))
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{
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if (arf_is_neg_inf(x))
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arf_nan(z);
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else
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arf_set(z, x);
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return 0;
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}
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if (ARF_SGNBIT(x))
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{
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arf_nan(z);
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return 0;
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}
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fmpz_init(q);
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fmpz_init(r);
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/* x = m * 2^e where e = qk + r */
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/* x^(1/k) = (m * 2^(qk+r))^(1/k) */
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/* x^(1/k) = (m * 2^r)^(1/k) * 2^q */
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fmpz_set_ui(r, k);
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fmpz_fdiv_qr(q, r, ARF_EXPREF(x), r);
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ARF_GET_MPN_READONLY(xptr, xn, x);
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zn = (prec + FLINT_BITS - 1) / FLINT_BITS;
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zf->_mpfr_d = tmp = flint_malloc(zn * sizeof(mp_limb_t));
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zf->_mpfr_prec = prec;
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zf->_mpfr_sign = 1;
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zf->_mpfr_exp = 0;
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xf->_mpfr_d = (mp_ptr) xptr;
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xf->_mpfr_prec = xn * FLINT_BITS;
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xf->_mpfr_sign = 1;
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xf->_mpfr_exp = fmpz_get_ui(r);
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inexact = mpfr_root(zf, xf, k, arf_rnd_to_mpfr(rnd));
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inexact = (inexact != 0);
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val = 0;
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while (tmp[val] == 0)
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val++;
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ARF_GET_MPN_WRITE(zptr, zn - val, z);
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flint_mpn_copyi(zptr, tmp + val, zn - val);
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fmpz_add_si(ARF_EXPREF(z), q, zf->_mpfr_exp);
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flint_free(tmp);
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fmpz_clear(q);
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fmpz_clear(r);
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return inexact;
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}
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