mirror of
https://github.com/vale981/arb
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102 lines
2.5 KiB
C
102 lines
2.5 KiB
C
/*=============================================================================
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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
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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ARB is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with ARB; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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=============================================================================*/
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/******************************************************************************
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Copyright (C) 2013 Fredrik Johansson
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******************************************************************************/
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#include "fmpcb.h"
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void
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fmpcb_sqrt(fmpcb_t y, const fmpcb_t x, long prec)
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{
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fmprb_t r, t, u;
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long wp;
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#define a fmpcb_realref(x)
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#define b fmpcb_imagref(x)
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#define c fmpcb_realref(y)
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#define d fmpcb_imagref(y)
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if (fmprb_is_zero(b))
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{
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if (fmprb_is_nonnegative(a))
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{
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fmprb_sqrt(c, a, prec);
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fmprb_zero(d);
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return;
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}
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else if (fmprb_is_nonpositive(a))
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{
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fmprb_neg(d, a);
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fmprb_sqrt(d, d, prec);
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fmprb_zero(c);
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return;
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}
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}
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if (fmprb_is_zero(a))
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{
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if (fmprb_is_nonnegative(b))
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{
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fmprb_mul_2exp_si(c, b, -1);
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fmprb_sqrt(c, c, prec);
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fmprb_set(d, c);
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return;
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}
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else if (fmprb_is_nonpositive(b))
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{
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fmprb_mul_2exp_si(c, b, -1);
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fmprb_neg(c, c);
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fmprb_sqrt(c, c, prec);
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fmprb_neg(d, c);
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return;
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}
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}
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/* sqrt(a+bi) = sqrt((r+a)/2) + b/sqrt(2*(r+a))*i, r = |a+bi| */
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wp = prec + 4;
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fmprb_init(r);
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fmprb_init(t);
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fmprb_init(u);
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fmpcb_abs(r, x, wp);
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fmprb_add(t, r, a, wp);
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fmprb_mul_2exp_si(u, t, 1);
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fmprb_sqrt(u, u, wp);
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fmprb_div(d, b, u, prec);
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fmprb_set_round(c, u, prec);
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fmprb_mul_2exp_si(c, c, -1);
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fmprb_clear(r);
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fmprb_clear(t);
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fmprb_clear(u);
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#undef a
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#undef b
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#undef c
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#undef d
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}
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