arb/fmpcb/root.c
2013-10-22 11:41:58 +02:00

109 lines
2.9 KiB
C

/*=============================================================================
This file is part of ARB.
ARB is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
ARB is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with ARB; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
=============================================================================*/
/******************************************************************************
Copyright (C) 2012 Fredrik Johansson
******************************************************************************/
#include "fmpcb.h"
void
fmpcb_root_exp(fmpcb_t r, const fmpcb_t a, long m, long index, long prec)
{
if (m == 1)
fmpcb_set_round(r, a, prec);
else if (m == -1)
fmpcb_inv(r, a, prec);
else
{
fmpcb_log(r, a, prec);
if (index != 0)
{
fmprb_t t;
fmprb_init(t);
fmprb_const_pi(t, prec);
fmprb_mul_2exp_si(t, t, 1);
fmprb_mul_si(t, t, index, prec);
fmprb_add(fmpcb_imagref(r), fmpcb_imagref(r), t, prec);
fmprb_clear(t);
}
fmpcb_div_si(r, r, m, prec);
fmpcb_exp(r, r, prec);
}
}
void
fmpcb_root_newton(fmpcb_t r, const fmpcb_t a, long m, long index, long prec)
{
if (m == 1)
fmpcb_set_round(r, a, prec);
else if (m == -1)
fmpcb_inv(r, a, prec);
else
{
long startprec;
fmpcb_t t;
fmpcb_init(t);
startprec = 100;
fmpcb_root_exp(t, a, -FLINT_ABS(m), index, startprec);
/* note: should check isolation first */
fmpcb_invroot_newton(t, a, FLINT_ABS(m), t, startprec, prec);
if (m < 0)
{
fmpcb_set(r, t);
}
else
{
if (fmpcb_is_one(a))
fmpcb_conj(r, t);
else if (m == 2)
fmpcb_mul(r, t, a, prec);
else
fmpcb_inv(r, t, prec);
}
fmpcb_clear(t);
}
}
void
fmpcb_root(fmpcb_t r, const fmpcb_t a, long m, long index, long prec)
{
if (m == 1)
fmpcb_set_round(r, a, prec);
else if (m == -1)
fmpcb_inv(r, a, prec);
else if (m == 2)
fmpcb_sqrt(r, a, prec);
else if (m == -2)
fmpcb_rsqrt(r, a, prec);
else if (prec < 300 || !fmpcb_is_exact(a) || (m == LONG_MIN))
fmpcb_root_exp(r, a, m, index, prec);
else
fmpcb_root_newton(r, a, m, index, prec);
}