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/* multiroots/broyden.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.
*/
#include <config.h>
#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <float.h>
#include <gsl/gsl_math.h>
#include <gsl/gsl_errno.h>
#include <gsl/gsl_multiroots.h>
#include <gsl/gsl_linalg.h>
#include "enorm.c"
/* Broyden's method. It is not an efficient or modern algorithm but
gives an example of a rank-1 update.
C.G. Broyden, "A Class of Methods for Solving Nonlinear
Simultaneous Equations", Mathematics of Computation, vol 19 (1965),
p 577-593
*/
typedef struct
{
gsl_matrix *H;
gsl_matrix *lu;
gsl_permutation *permutation;
gsl_vector *v;
gsl_vector *w;
gsl_vector *y;
gsl_vector *p;
gsl_vector *fnew;
gsl_vector *x_trial;
double phi;
}
broyden_state_t;
static int broyden_alloc (void *vstate, size_t n);
static int broyden_set (void *vstate, gsl_multiroot_function * function, gsl_vector * x, gsl_vector * f, gsl_vector * dx);
static int broyden_iterate (void *vstate, gsl_multiroot_function * function, gsl_vector * x, gsl_vector * f, gsl_vector * dx);
static void broyden_free (void *vstate);
static int
broyden_alloc (void *vstate, size_t n)
{
broyden_state_t *state = (broyden_state_t *) vstate;
gsl_vector *v, *w, *y, *fnew, *x_trial, *p;
gsl_permutation *perm;
gsl_matrix *m, *H;
m = gsl_matrix_calloc (n, n);
if (m == 0)
{
GSL_ERROR ("failed to allocate space for lu", GSL_ENOMEM);
}
state->lu = m;
perm = gsl_permutation_calloc (n);
if (perm == 0)
{
gsl_matrix_free (m);
GSL_ERROR ("failed to allocate space for permutation", GSL_ENOMEM);
}
state->permutation = perm;
H = gsl_matrix_calloc (n, n);
if (H == 0)
{
gsl_permutation_free (perm);
gsl_matrix_free (m);
GSL_ERROR ("failed to allocate space for d", GSL_ENOMEM);
}
state->H = H;
v = gsl_vector_calloc (n);
if (v == 0)
{
gsl_matrix_free (H);
gsl_permutation_free (perm);
gsl_matrix_free (m);
GSL_ERROR ("failed to allocate space for v", GSL_ENOMEM);
}
state->v = v;
w = gsl_vector_calloc (n);
if (w == 0)
{
gsl_vector_free (v);
gsl_matrix_free (H);
gsl_permutation_free (perm);
gsl_matrix_free (m);
GSL_ERROR ("failed to allocate space for w", GSL_ENOMEM);
}
state->w = w;
y = gsl_vector_calloc (n);
if (y == 0)
{
gsl_vector_free (w);
gsl_vector_free (v);
gsl_matrix_free (H);
gsl_permutation_free (perm);
gsl_matrix_free (m);
GSL_ERROR ("failed to allocate space for y", GSL_ENOMEM);
}
state->y = y;
fnew = gsl_vector_calloc (n);
if (fnew == 0)
{
gsl_vector_free (y);
gsl_vector_free (w);
gsl_vector_free (v);
gsl_matrix_free (H);
gsl_permutation_free (perm);
gsl_matrix_free (m);
GSL_ERROR ("failed to allocate space for fnew", GSL_ENOMEM);
}
state->fnew = fnew;
x_trial = gsl_vector_calloc (n);
if (x_trial == 0)
{
gsl_vector_free (fnew);
gsl_vector_free (y);
gsl_vector_free (w);
gsl_vector_free (v);
gsl_matrix_free (H);
gsl_permutation_free (perm);
gsl_matrix_free (m);
GSL_ERROR ("failed to allocate space for x_trial", GSL_ENOMEM);
}
state->x_trial = x_trial;
p = gsl_vector_calloc (n);
if (p == 0)
{
gsl_vector_free (x_trial);
gsl_vector_free (fnew);
gsl_vector_free (y);
gsl_vector_free (w);
gsl_vector_free (v);
gsl_matrix_free (H);
gsl_permutation_free (perm);
gsl_matrix_free (m);
GSL_ERROR ("failed to allocate space for p", GSL_ENOMEM);
}
state->p = p;
return GSL_SUCCESS;
}
static int
broyden_set (void *vstate, gsl_multiroot_function * function, gsl_vector * x, gsl_vector * f, gsl_vector * dx)
{
broyden_state_t *state = (broyden_state_t *) vstate;
size_t i, j, n = function->n;
int signum = 0;
GSL_MULTIROOT_FN_EVAL (function, x, f);
gsl_multiroot_fdjacobian (function, x, f, GSL_SQRT_DBL_EPSILON, state->lu);
gsl_linalg_LU_decomp (state->lu, state->permutation, &signum);
gsl_linalg_LU_invert (state->lu, state->permutation, state->H);
for (i = 0; i < n; i++)
for (j = 0; j < n; j++)
gsl_matrix_set(state->H,i,j,-gsl_matrix_get(state->H,i,j));
for (i = 0; i < n; i++)
{
gsl_vector_set (dx, i, 0.0);
}
state->phi = enorm (f);
return GSL_SUCCESS;
}
static int
broyden_iterate (void *vstate, gsl_multiroot_function * function, gsl_vector * x, gsl_vector * f, gsl_vector * dx)
{
broyden_state_t *state = (broyden_state_t *) vstate;
double phi0, phi1, t, lambda;
gsl_matrix *H = state->H;
gsl_vector *p = state->p;
gsl_vector *y = state->y;
gsl_vector *v = state->v;
gsl_vector *w = state->w;
gsl_vector *fnew = state->fnew;
gsl_vector *x_trial = state->x_trial;
gsl_matrix *lu = state->lu;
gsl_permutation *perm = state->permutation;
size_t i, j, iter;
size_t n = function->n;
/* p = H f */
for (i = 0; i < n; i++)
{
double sum = 0;
for (j = 0; j < n; j++)
{
sum += gsl_matrix_get (H, i, j) * gsl_vector_get (f, j);
}
gsl_vector_set (p, i, sum);
}
t = 1;
iter = 0;
phi0 = state->phi;
new_step:
for (i = 0; i < n; i++)
{
double pi = gsl_vector_get (p, i);
double xi = gsl_vector_get (x, i);
gsl_vector_set (x_trial, i, xi + t * pi);
}
{
int status = GSL_MULTIROOT_FN_EVAL (function, x_trial, fnew);
if (status != GSL_SUCCESS)
{
return GSL_EBADFUNC;
}
}
phi1 = enorm (fnew);
iter++ ;
if (phi1 > phi0 && iter < 10 && t > 0.1)
{
/* full step goes uphill, take a reduced step instead */
double theta = phi1 / phi0;
t *= (sqrt (1.0 + 6.0 * theta) - 1.0) / (3.0 * theta);
goto new_step;
}
if (phi1 > phi0)
{
/* need to recompute Jacobian */
int signum = 0;
gsl_multiroot_fdjacobian (function, x, f, GSL_SQRT_DBL_EPSILON, lu);
for (i = 0; i < n; i++)
for (j = 0; j < n; j++)
gsl_matrix_set(lu,i,j,-gsl_matrix_get(lu,i,j));
gsl_linalg_LU_decomp (lu, perm, &signum);
gsl_linalg_LU_invert (lu, perm, H);
gsl_linalg_LU_solve (lu, perm, f, p);
t = 1;
for (i = 0; i < n; i++)
{
double pi = gsl_vector_get (p, i);
double xi = gsl_vector_get (x, i);
gsl_vector_set (x_trial, i, xi + t * pi);
}
{
int status = GSL_MULTIROOT_FN_EVAL (function, x_trial, fnew);
if (status != GSL_SUCCESS)
{
return GSL_EBADFUNC;
}
}
phi1 = enorm (fnew);
}
/* y = f' - f */
for (i = 0; i < n; i++)
{
double yi = gsl_vector_get (fnew, i) - gsl_vector_get (f, i);
gsl_vector_set (y, i, yi);
}
/* v = H y */
for (i = 0; i < n; i++)
{
double sum = 0;
for (j = 0; j < n; j++)
{
sum += gsl_matrix_get (H, i, j) * gsl_vector_get (y, j);
}
gsl_vector_set (v, i, sum);
}
/* lambda = p . v */
lambda = 0;
for (i = 0; i < n; i++)
{
lambda += gsl_vector_get (p, i) * gsl_vector_get (v, i);
}
if (lambda == 0)
{
GSL_ERROR ("approximation to Jacobian has collapsed", GSL_EZERODIV) ;
}
/* v' = v + t * p */
for (i = 0; i < n; i++)
{
double vi = gsl_vector_get (v, i) + t * gsl_vector_get (p, i);
gsl_vector_set (v, i, vi);
}
/* w^T = p^T H */
for (i = 0; i < n; i++)
{
double sum = 0;
for (j = 0; j < n; j++)
{
sum += gsl_matrix_get (H, j, i) * gsl_vector_get (p, j);
}
gsl_vector_set (w, i, sum);
}
/* Hij -> Hij - (vi wj / lambda) */
for (i = 0; i < n; i++)
{
double vi = gsl_vector_get (v, i);
for (j = 0; j < n; j++)
{
double wj = gsl_vector_get (w, j);
double Hij = gsl_matrix_get (H, i, j) - vi * wj / lambda;
gsl_matrix_set (H, i, j, Hij);
}
}
/* copy fnew into f */
gsl_vector_memcpy (f, fnew);
/* copy x_trial into x */
gsl_vector_memcpy (x, x_trial);
for (i = 0; i < n; i++)
{
double pi = gsl_vector_get (p, i);
gsl_vector_set (dx, i, t * pi);
}
state->phi = phi1;
return GSL_SUCCESS;
}
static void
broyden_free (void *vstate)
{
broyden_state_t *state = (broyden_state_t *) vstate;
gsl_matrix_free (state->H);
gsl_matrix_free (state->lu);
gsl_permutation_free (state->permutation);
gsl_vector_free (state->v);
gsl_vector_free (state->w);
gsl_vector_free (state->y);
gsl_vector_free (state->p);
gsl_vector_free (state->fnew);
gsl_vector_free (state->x_trial);
}
static const gsl_multiroot_fsolver_type broyden_type =
{"broyden", /* name */
sizeof (broyden_state_t),
&broyden_alloc,
&broyden_set,
&broyden_iterate,
&broyden_free};
const gsl_multiroot_fsolver_type *gsl_multiroot_fsolver_broyden = &broyden_type;