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/* poly/zsolve.c
*
* Copyright (C) 1996, 1997, 1998, 1999, 2000 Brian Gough
*
* This program 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.
*
* This program 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 this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
/* zsolve.c - finds the complex roots of = 0 */
#include <config.h>
#include <math.h>
#include <stdlib.h>
#include <gsl/gsl_math.h>
#include <gsl/gsl_errno.h>
#include <gsl/gsl_complex.h>
#include <gsl/gsl_poly.h>
/* C-style matrix elements */
#define MAT(m,i,j,n) ((m)[(i)*(n) + (j)])
/* Fortran-style matrix elements */
#define FMAT(m,i,j,n) ((m)[((i)-1)*(n) + ((j)-1)])
#include "companion.c"
#include "balance.c"
#include "qr.c"
int
gsl_poly_complex_solve (const double *a, size_t n,
gsl_poly_complex_workspace * w,
gsl_complex_packed_ptr z)
{
int status;
double *m;
if (n == 0)
{
GSL_ERROR ("number of terms must be a positive integer", GSL_EINVAL);
}
if (n == 1)
{
GSL_ERROR ("cannot solve for only one term", GSL_EINVAL);
}
if (a[n - 1] == 0)
{
GSL_ERROR ("leading term of polynomial must be non-zero", GSL_EINVAL) ;
}
if (w->nc != n - 1)
{
GSL_ERROR ("size of workspace does not match polynomial", GSL_EINVAL);
}
m = w->matrix;
set_companion_matrix (a, n - 1, m);
balance_companion_matrix (m, n - 1);
status = qr_companion (m, n - 1, z);
if (status)
{
GSL_ERROR("root solving qr method failed to converge", GSL_EFAILED);
}
return GSL_SUCCESS;
}
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