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/* multimin/vector_bfgs.c
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*
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* Copyright (C) 1996, 1997, 1998, 1999, 2000 Fabrice Rossi
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*
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* This program 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 3 of the License, or (at
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* your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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/* vector_bfgs.c -- Limited memory Broyden-Fletcher-Goldfarb-Shanno method */
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/* Modified by Brian Gough to use single iteration structure */
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#include <config.h>
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#include <gsl/gsl_multimin.h>
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#include <gsl/gsl_blas.h>
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#include "directional_minimize.c"
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typedef struct
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{
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int iter;
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double step;
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double max_step;
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double tol;
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gsl_vector *x1;
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gsl_vector *dx1;
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gsl_vector *x2;
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double g0norm;
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double pnorm;
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gsl_vector *p;
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gsl_vector *x0;
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gsl_vector *g0;
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gsl_vector *dx0;
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gsl_vector *dg0;
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}
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vector_bfgs_state_t;
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static int
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vector_bfgs_alloc (void *vstate, size_t n)
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{
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vector_bfgs_state_t *state = (vector_bfgs_state_t *) vstate;
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state->x1 = gsl_vector_calloc (n);
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if (state->x1 == 0)
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{
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GSL_ERROR ("failed to allocate space for x1", GSL_ENOMEM);
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}
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state->dx1 = gsl_vector_calloc (n);
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if (state->dx1 == 0)
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{
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gsl_vector_free (state->x1);
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GSL_ERROR ("failed to allocate space for dx1", GSL_ENOMEM);
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}
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state->x2 = gsl_vector_calloc (n);
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if (state->x2 == 0)
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{
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gsl_vector_free (state->dx1);
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gsl_vector_free (state->x1);
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GSL_ERROR ("failed to allocate space for x2", GSL_ENOMEM);
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}
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state->p = gsl_vector_calloc (n);
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if (state->p == 0)
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{
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gsl_vector_free (state->x2);
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gsl_vector_free (state->dx1);
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gsl_vector_free (state->x1);
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GSL_ERROR ("failed to allocate space for p", GSL_ENOMEM);
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}
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state->x0 = gsl_vector_calloc (n);
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if (state->x0 == 0)
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{
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gsl_vector_free (state->p);
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gsl_vector_free (state->x2);
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gsl_vector_free (state->dx1);
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gsl_vector_free (state->x1);
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GSL_ERROR ("failed to allocate space for g0", GSL_ENOMEM);
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}
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state->g0 = gsl_vector_calloc (n);
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if (state->g0 == 0)
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{
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gsl_vector_free (state->x0);
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gsl_vector_free (state->p);
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gsl_vector_free (state->x2);
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gsl_vector_free (state->dx1);
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gsl_vector_free (state->x1);
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GSL_ERROR ("failed to allocate space for g0", GSL_ENOMEM);
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}
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state->dx0 = gsl_vector_calloc (n);
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if (state->dx0 == 0)
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{
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gsl_vector_free (state->g0);
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gsl_vector_free (state->x0);
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gsl_vector_free (state->p);
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gsl_vector_free (state->x2);
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gsl_vector_free (state->dx1);
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gsl_vector_free (state->x1);
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GSL_ERROR ("failed to allocate space for g0", GSL_ENOMEM);
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}
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state->dg0 = gsl_vector_calloc (n);
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if (state->dg0 == 0)
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{
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gsl_vector_free (state->dx0);
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gsl_vector_free (state->g0);
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gsl_vector_free (state->x0);
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gsl_vector_free (state->p);
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gsl_vector_free (state->x2);
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gsl_vector_free (state->dx1);
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gsl_vector_free (state->x1);
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GSL_ERROR ("failed to allocate space for g0", GSL_ENOMEM);
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}
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return GSL_SUCCESS;
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}
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static int
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vector_bfgs_set (void *vstate, gsl_multimin_function_fdf * fdf,
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const gsl_vector * x, double *f, gsl_vector * gradient,
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double step_size, double tol)
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{
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vector_bfgs_state_t *state = (vector_bfgs_state_t *) vstate;
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state->iter = 0;
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state->step = step_size;
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state->max_step = step_size;
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state->tol = tol;
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GSL_MULTIMIN_FN_EVAL_F_DF (fdf, x, f, gradient);
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/* Use the gradient as the initial direction */
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gsl_vector_memcpy (state->x0, x);
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gsl_vector_memcpy (state->p, gradient);
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gsl_vector_memcpy (state->g0, gradient);
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{
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double gnorm = gsl_blas_dnrm2 (gradient);
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state->pnorm = gnorm;
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state->g0norm = gnorm;
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}
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return GSL_SUCCESS;
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}
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static void
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vector_bfgs_free (void *vstate)
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{
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vector_bfgs_state_t *state = (vector_bfgs_state_t *) vstate;
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gsl_vector_free (state->dg0);
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gsl_vector_free (state->dx0);
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gsl_vector_free (state->g0);
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gsl_vector_free (state->x0);
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gsl_vector_free (state->p);
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gsl_vector_free (state->x2);
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gsl_vector_free (state->dx1);
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gsl_vector_free (state->x1);
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}
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static int
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vector_bfgs_restart (void *vstate)
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{
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vector_bfgs_state_t *state = (vector_bfgs_state_t *) vstate;
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state->iter = 0;
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return GSL_SUCCESS;
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}
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static int
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vector_bfgs_iterate (void *vstate, gsl_multimin_function_fdf * fdf,
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gsl_vector * x, double *f,
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gsl_vector * gradient, gsl_vector * dx)
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{
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vector_bfgs_state_t *state = (vector_bfgs_state_t *) vstate;
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gsl_vector *x1 = state->x1;
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gsl_vector *dx1 = state->dx1;
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gsl_vector *x2 = state->x2;
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gsl_vector *p = state->p;
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gsl_vector *g0 = state->g0;
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gsl_vector *x0 = state->x0;
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double pnorm = state->pnorm;
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double g0norm = state->g0norm;
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double fa = *f, fb, fc;
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double dir;
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double stepa = 0.0, stepb, stepc = state->step, tol = state->tol;
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double g1norm;
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double pg;
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if (pnorm == 0.0 || g0norm == 0.0)
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{
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gsl_vector_set_zero (dx);
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return GSL_ENOPROG;
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}
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/* Determine which direction is downhill, +p or -p */
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gsl_blas_ddot (p, gradient, &pg;;
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dir = (pg >= 0.0) ? +1.0 : -1.0;
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/* Compute new trial point at x_c= x - step * p, where p is the
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current direction */
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take_step (x, p, stepc, dir / pnorm, x1, dx);
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/* Evaluate function and gradient at new point xc */
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fc = GSL_MULTIMIN_FN_EVAL_F (fdf, x1);
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if (fc < fa)
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{
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/* Success, reduced the function value */
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state->step = stepc * 2.0;
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*f = fc;
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gsl_vector_memcpy (x, x1);
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GSL_MULTIMIN_FN_EVAL_DF (fdf, x1, gradient);
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return GSL_SUCCESS;
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}
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#ifdef DEBUG
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printf ("got stepc = %g fc = %g\n", stepc, fc);
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#endif
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/* Do a line minimisation in the region (xa,fa) (xc,fc) to find an
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intermediate (xb,fb) satisifying fa > fb < fc. Choose an initial
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xb based on parabolic interpolation */
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intermediate_point (fdf, x, p, dir / pnorm, pg,
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stepa, stepc, fa, fc, x1, dx1, gradient, &stepb, &fb;;
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if (stepb == 0.0)
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{
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return GSL_ENOPROG;
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}
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|
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minimize (fdf, x, p, dir / pnorm,
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stepa, stepb, stepc, fa, fb, fc, tol,
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x1, dx1, x2, dx, gradient, &(state->step), f, &g1norm);
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gsl_vector_memcpy (x, x2);
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/* Choose a new direction for the next step */
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state->iter = (state->iter + 1) % x->size;
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if (state->iter == 0)
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{
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gsl_vector_memcpy (p, gradient);
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state->pnorm = g1norm;
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}
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else
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{
|
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/* This is the BFGS update: */
|
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/* p' = g1 - A dx - B dg */
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/* A = - (1+ dg.dg/dx.dg) B + dg.g/dx.dg */
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/* B = dx.g/dx.dg */
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gsl_vector *dx0 = state->dx0;
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gsl_vector *dg0 = state->dg0;
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double dxg, dgg, dxdg, dgnorm, A, B;
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67cb25 |
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/* dx0 = x - x0 */
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gsl_vector_memcpy (dx0, x);
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gsl_blas_daxpy (-1.0, x0, dx0);
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67cb25 |
|
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67cb25 |
/* dg0 = g - g0 */
|
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67cb25 |
gsl_vector_memcpy (dg0, gradient);
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Packit |
67cb25 |
gsl_blas_daxpy (-1.0, g0, dg0);
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|
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gsl_blas_ddot (dx0, gradient, &dxg);
|
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67cb25 |
gsl_blas_ddot (dg0, gradient, &dgg);
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67cb25 |
gsl_blas_ddot (dx0, dg0, &dxdg);
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67cb25 |
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dgnorm = gsl_blas_dnrm2 (dg0);
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67cb25 |
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|
Packit |
67cb25 |
if (dxdg != 0)
|
|
Packit |
67cb25 |
{
|
|
Packit |
67cb25 |
B = dxg / dxdg;
|
|
Packit |
67cb25 |
A = -(1.0 + dgnorm * dgnorm / dxdg) * B + dgg / dxdg;
|
|
Packit |
67cb25 |
}
|
|
Packit |
67cb25 |
else
|
|
Packit |
67cb25 |
{
|
|
Packit |
67cb25 |
B = 0;
|
|
Packit |
67cb25 |
A = 0;
|
|
Packit |
67cb25 |
}
|
|
Packit |
67cb25 |
|
|
Packit |
67cb25 |
gsl_vector_memcpy (p, gradient);
|
|
Packit |
67cb25 |
gsl_blas_daxpy (-A, dx0, p);
|
|
Packit |
67cb25 |
gsl_blas_daxpy (-B, dg0, p);
|
|
Packit |
67cb25 |
|
|
Packit |
67cb25 |
state->pnorm = gsl_blas_dnrm2 (p);
|
|
Packit |
67cb25 |
}
|
|
Packit |
67cb25 |
|
|
Packit |
67cb25 |
gsl_vector_memcpy (g0, gradient);
|
|
Packit |
67cb25 |
gsl_vector_memcpy (x0, x);
|
|
Packit |
67cb25 |
state->g0norm = gsl_blas_dnrm2 (g0);
|
|
Packit |
67cb25 |
|
|
Packit |
67cb25 |
#ifdef DEBUG
|
|
Packit |
67cb25 |
printf ("updated directions\n");
|
|
Packit |
67cb25 |
printf ("p: ");
|
|
Packit |
67cb25 |
gsl_vector_fprintf (stdout, p, "%g");
|
|
Packit |
67cb25 |
printf ("g: ");
|
|
Packit |
67cb25 |
gsl_vector_fprintf (stdout, gradient, "%g");
|
|
Packit |
67cb25 |
#endif
|
|
Packit |
67cb25 |
|
|
Packit |
67cb25 |
return GSL_SUCCESS;
|
|
Packit |
67cb25 |
}
|
|
Packit |
67cb25 |
|
|
Packit |
67cb25 |
static const gsl_multimin_fdfminimizer_type vector_bfgs_type = {
|
|
Packit |
67cb25 |
"vector_bfgs", /* name */
|
|
Packit |
67cb25 |
sizeof (vector_bfgs_state_t),
|
|
Packit |
67cb25 |
&vector_bfgs_alloc,
|
|
Packit |
67cb25 |
&vector_bfgs_set,
|
|
Packit |
67cb25 |
&vector_bfgs_iterate,
|
|
Packit |
67cb25 |
&vector_bfgs_restart,
|
|
Packit |
67cb25 |
&vector_bfgs_free
|
|
Packit |
67cb25 |
};
|
|
Packit |
67cb25 |
|
|
Packit |
67cb25 |
const gsl_multimin_fdfminimizer_type
|
|
Packit |
67cb25 |
* gsl_multimin_fdfminimizer_vector_bfgs = &vector_bfgs_type;
|