+/* $Id$ */
+
+/* Copyright (c) 2007 Arnaud Legrand, Pedro Velho. All rights reserved. */
+
+/* This program is free software; you can redistribute it and/or modify it
+ * under the terms of the license (GNU LGPL) which comes with this package. */
+
+/*
+ * Modelling the proportional fairness using the Lagrange Optimization
+ * Approach. For a detailed description see:
+ * "ssh://username@scm.gforge.inria.fr/svn/memo/people/pvelho/lagrange/ppf.ps".
+ */
+#include "xbt/log.h"
+#include "xbt/sysdep.h"
+#include "xbt/mallocator.h"
+#include "maxmin_private.h"
+
+#include <stdlib.h>
+#ifndef MATH
+#include <math.h>
+#endif
+
+
+XBT_LOG_NEW_DEFAULT_SUBCATEGORY(surf_lagrange, surf,
+ "Logging specific to SURF (lagrange)");
+
+void lagrange_solve(lmm_system_t sys)
+{
+
+ /*
+ * Lagrange Variables.
+ */
+ double epsilon_min_error = 1e-6;
+ double overall_error = 1;
+ double sigma_step = 0.5e-3;
+ double capacity_error, bound_error;
+ double sum_capacity = 0;
+ double sum_bound = 0;
+
+
+ /*
+ * Variables to manipulate the data structure proposed to model the maxmin
+ * fairness. See docummentation for more details.
+ */
+ lmm_element_t elem = NULL;
+ xbt_swag_t cnst_list = NULL;
+ lmm_constraint_t cnst1 = NULL;
+ lmm_constraint_t cnst2 = NULL;
+ xbt_swag_t var_list = NULL;
+ xbt_swag_t elem_list = NULL;
+ lmm_variable_t var1 = NULL;
+ lmm_variable_t var2 = NULL;
+
+
+ /*
+ * Auxiliar variables.
+ */
+ int iteration=0;
+ int max_iterations=100000;
+ double mu_partial=0;
+ double lambda_partial=0;
+
+
+ if ( !(sys->modified))
+ return;
+
+ /*
+ * Initialize the var list variable with only the active variables.
+ * Associate an index in the swag variables and compute the sum
+ * of all round trip time constraints. May change depending on the
+ * function f(x).
+ */
+ var_list = &(sys->active_variable_set);
+ i=0;
+ xbt_swag_foreach(var1, var_list) {
+ if(var1->weight != 0.0){
+ i++;
+ sum_bound += var1->bound;
+ }
+ }
+
+ /*
+ * Compute the sum of all capacities constraints. May change depending
+ * on the function f(x).
+ */
+ cnst_list=&(sys->active_constraint_set);
+ xbt_swag_foreach(cnst1, cnst_list) {
+ sum_capacity += cnst1->value;
+ }
+
+
+ /*
+ * While doesn't reach a minimun error or a number maximum of iterations.
+ */
+ while(overall_error > epsilon_min_error && iteration < max_iterations){
+
+ iteration++;
+
+
+
+ /* d Dual
+ * Compute the value of ----------- (\lambda^k, \mu^k) this portion
+ * d \mu_i^k
+ * of code depends on function f(x).
+ */
+ bound_error = 0;
+ xbt_swag_foreach(var1, var_list) {
+
+ mu_partial = 0;
+
+ //for each link elem1 that uses flow of variable var1 do
+ //mu_partial += elem1->weight + var1->bound;
+
+ mu_partial = - (1 / mu_partial) + sum_bound;
+
+ var1->bound = var1->bound + sigma_step * mu_partial;
+ }
+
+
+
+ /*
+ * Verify for each capacity constraint (lambda) the error associated.
+ */
+ xbt_swag_foreach(cnst1, cnst_list) {
+ cnst2 = xbt_swag_getNext(cnst1,(var_list)->offset);
+ if(cnst2 != NULL){
+ capacity_error += fabs(cnst1->value - cnsts2->value);
+ }
+ }
+
+ /*
+ * Verify for each variable the error of round trip time constraint (mu).
+ */
+ bound_error = 0;
+ xbt_swag_foreach(var1, var_list) {
+ var2 = xbt_swag_getNext(var1,(var_list)->offset);
+ if(var2 != NULL){
+ bound_error += fabs( var2->weight - var1->weight);
+ }
+ }
+
+ overall_error = capacity_error + bound_error;
+ }
+
+}
