arb/fmpcb_poly/root_inclusion.c

66 lines
2.1 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_poly.h"
void
_fmpcb_poly_root_inclusion(fmpcb_t r, const fmpcb_t m,
fmpcb_srcptr poly,
fmpcb_srcptr polyder, long len, long prec)
{
fmpcb_t t;
fmpr_t u, v;
fmpcb_init(t);
fmpr_init(u);
fmpr_init(v);
fmpcb_set(r, m);
fmpr_zero(fmprb_radref(fmpcb_realref(r)));
fmpr_zero(fmprb_radref(fmpcb_imagref(r)));
_fmpcb_poly_evaluate(t, poly, len, r, prec);
fmpcb_get_abs_ubound_fmpr(u, t, FMPRB_RAD_PREC);
/* it could happen that we have an exact root, in which case
we should avoid dividing by the derivative */
if (!fmpr_is_zero(u))
{
_fmpcb_poly_evaluate(t, polyder, len - 1, r, prec);
fmpcb_inv(t, t, FMPRB_RAD_PREC);
fmpcb_get_abs_ubound_fmpr(v, t, FMPRB_RAD_PREC);
fmpr_mul(u, u, v, FMPRB_RAD_PREC, FMPR_RND_UP);
fmpr_mul_ui(u, u, len - 1, FMPRB_RAD_PREC, FMPR_RND_UP);
}
fmpr_set(fmprb_radref(fmpcb_realref(r)), u);
fmpr_set(fmprb_radref(fmpcb_imagref(r)), u);
fmpr_clear(u);
fmpr_clear(v);
fmpcb_clear(t);
}