X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/c027c476705c1c88c5c76570ccdd75809fbc3af2..cf56a22da60094d8e7f14b1457526dc194d40226:/src/surf/maxmin.c

diff --git a/src/surf/maxmin.c b/src/surf/maxmin.c
index e36c5c88fe..3177a75fe1 100644
--- a/src/surf/maxmin.c
+++ b/src/surf/maxmin.c
@@ -15,7 +15,7 @@
 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(surf_maxmin, surf,
 				"Logging specific to SURF (maxmin)");
 
-static void* lmm_variable_mallocator_new_f(void);
+static void *lmm_variable_mallocator_new_f(void);
 static void lmm_variable_mallocator_free_f(void *var);
 static void lmm_variable_mallocator_reset_f(void *var);
 
@@ -69,7 +69,7 @@ void lmm_variable_disable(lmm_system_t sys, lmm_variable_t var)
   int i;
   lmm_element_t elem = NULL;
 
-  XBT_IN2("(sys=%p, var=%p)",sys,var);
+  XBT_IN2("(sys=%p, var=%p)", sys, var);
   sys->modified = 1;
 
   for (i = 0; i < var->cnsts_number; i++) {
@@ -131,15 +131,18 @@ void lmm_constraint_free(lmm_system_t sys, lmm_constraint_t cnst)
   lmm_cnst_free(sys, cnst);
 }
 
-static void* lmm_variable_mallocator_new_f(void) {
+static void *lmm_variable_mallocator_new_f(void)
+{
   return xbt_new(s_lmm_variable_t, 1);
 }
 
-static void lmm_variable_mallocator_free_f(void *var) {
+static void lmm_variable_mallocator_free_f(void *var)
+{
   xbt_free(var);
 }
 
-static void lmm_variable_mallocator_reset_f(void *var) {
+static void lmm_variable_mallocator_reset_f(void *var)
+{
   /* memset to zero like calloc */
   memset(var, 0, sizeof(s_lmm_variable_t));
 }
@@ -152,12 +155,12 @@ lmm_variable_t lmm_variable_new(lmm_system_t sys, void *id,
   int i;
 
   XBT_IN5("(sys=%p, id=%p, weight=%f, bound=%f, num_cons =%d)",
-	  sys,id,weight,bound,number_of_constraints);
+	  sys, id, weight, bound, number_of_constraints);
 
   var = xbt_mallocator_get(sys->variable_mallocator);
   var->id = id;
   var->cnsts = xbt_new0(s_lmm_element_t, number_of_constraints);
-  for(i=0; i<number_of_constraints; i++) {
+  for (i = 0; i < number_of_constraints; i++) {
     /* Should be useless because of the 
        calloc but it seems to help valgrind... */
     var->cnsts[i].element_set_hookup.next = NULL;
@@ -169,20 +172,21 @@ lmm_variable_t lmm_variable_new(lmm_system_t sys, void *id,
     var->cnsts[i].value = 0.0;
   }
   var->cnsts_size = number_of_constraints;
-  var->cnsts_number = 0; /* Should be useless because of the 
-			    calloc but it seems to help valgrind... */
+  var->cnsts_number = 0;	/* Should be useless because of the 
+				   calloc but it seems to help valgrind... */
   var->weight = weight;
   var->bound = bound;
   var->value = 0.0;
-  var->df    = 1.0;
+  var->df = 0.0;
 
-  var->func_f    = func_f_def;
-  var->func_fp   = func_fp_def;
-  var->func_fpi  = func_fpi_def;
-  var->func_fpip = func_fpip_def;
+  var->func_f = func_f_def;
+  var->func_fp = func_fp_def;
+  var->func_fpi = func_fpi_def;
 
-  if(weight) xbt_swag_insert_at_head(var,&(sys->variable_set));
-  else xbt_swag_insert_at_tail(var,&(sys->variable_set));
+  if (weight)
+    xbt_swag_insert_at_head(var, &(sys->variable_set));
+  else
+    xbt_swag_insert_at_tail(var, &(sys->variable_set));
   XBT_OUT;
   return var;
 }
@@ -205,8 +209,7 @@ void lmm_expand(lmm_system_t sys, lmm_constraint_t cnst,
 
   sys->modified = 1;
 
-  xbt_assert0(var->cnsts_number < var->cnsts_size,
-	      "Too much constraints");
+  xbt_assert0(var->cnsts_number < var->cnsts_size, "Too much constraints");
 
   elem = &(var->cnsts[var->cnsts_number++]);
 
@@ -214,8 +217,10 @@ void lmm_expand(lmm_system_t sys, lmm_constraint_t cnst,
   elem->constraint = cnst;
   elem->variable = var;
 
-  if(var->weight) xbt_swag_insert_at_head(elem,&(elem->constraint->element_set));
-  else xbt_swag_insert_at_tail(elem,&(elem->constraint->element_set));
+  if (var->weight)
+    xbt_swag_insert_at_head(elem, &(elem->constraint->element_set));
+  else
+    xbt_swag_insert_at_tail(elem, &(elem->constraint->element_set));
 
   make_constraint_active(sys, cnst);
 }
@@ -223,28 +228,33 @@ void lmm_expand(lmm_system_t sys, lmm_constraint_t cnst,
 void lmm_expand_add(lmm_system_t sys, lmm_constraint_t cnst,
 		    lmm_variable_t var, double value)
 {
-  int i ; 
+  int i;
   sys->modified = 1;
 
-  for(i=0; i< var->cnsts_number ; i++)
-    if(var->cnsts[i].constraint == cnst) break;
-  
-  if(i<var->cnsts_number) var->cnsts[i].value +=value;
-  else lmm_expand(sys,cnst,var,value);
+  for (i = 0; i < var->cnsts_number; i++)
+    if (var->cnsts[i].constraint == cnst)
+      break;
+
+  if (i < var->cnsts_number)
+    var->cnsts[i].value += value;
+  else
+    lmm_expand(sys, cnst, var, value);
 }
 
 void lmm_elem_set_value(lmm_system_t sys, lmm_constraint_t cnst,
 			lmm_variable_t var, double value)
 {
-  int i ; 
+  int i;
 
-  for(i=0; i< var->cnsts_number ; i++)
-    if(var->cnsts[i].constraint == cnst) break;
+  for (i = 0; i < var->cnsts_number; i++)
+    if (var->cnsts[i].constraint == cnst)
+      break;
 
-  if(i<var->cnsts_number) {
-    var->cnsts[i].value =value;
+  if (i < var->cnsts_number) {
+    var->cnsts[i].value = value;
     sys->modified = 1;
-  } else DIE_IMPOSSIBLE;
+  } else
+    DIE_IMPOSSIBLE;
 }
 
 lmm_constraint_t lmm_get_cnst_from_var(lmm_system_t sys,
@@ -288,7 +298,7 @@ static void saturated_constraint_set_update(lmm_system_t sys,
 {
   lmm_constraint_t useless_cnst = NULL;
 
-  XBT_IN3("sys=%p, cnst=%p, min_usage=%f",sys,cnst,*min_usage);
+  XBT_IN3("sys=%p, cnst=%p, min_usage=%f", sys, cnst, *min_usage);
   if (cnst->usage <= 0) {
     XBT_OUT;
     return;
@@ -299,8 +309,8 @@ static void saturated_constraint_set_update(lmm_system_t sys,
   }
   if ((*min_usage < 0) || (*min_usage > cnst->remaining / cnst->usage)) {
     *min_usage = cnst->remaining / cnst->usage;
-    LOG3(xbt_log_priority_trace, 
-	 "min_usage=%f (cnst->remaining=%f, cnst->usage=%f)",*min_usage, 
+    LOG3(xbt_log_priority_trace,
+	 "min_usage=%f (cnst->remaining=%f, cnst->usage=%f)", *min_usage,
 	 cnst->remaining, cnst->usage);
     while ((useless_cnst =
 	    xbt_swag_getFirst(&(sys->saturated_constraint_set))))
@@ -324,7 +334,8 @@ static void saturated_variable_set_update(lmm_system_t sys)
   while ((cnst = xbt_swag_getFirst(cnst_list))) {
     elem_list = &(cnst->active_element_set);
     xbt_swag_foreach(elem, elem_list) {
-      if(elem->variable->weight<=0) break;
+      if (elem->variable->weight <= 0)
+	break;
       if ((elem->value > 0))
 	xbt_swag_insert(elem->variable, &(sys->saturated_variable_set));
     }
@@ -341,63 +352,77 @@ void lmm_print(lmm_system_t sys)
   xbt_swag_t var_list = NULL;
   xbt_swag_t elem_list = NULL;
   char print_buf[1024];
-  char *trace_buf=xbt_malloc0(sizeof(char));
-  double sum=0.0;
+  char *trace_buf = xbt_malloc0(sizeof(char));
+  double sum = 0.0;
 
   /* Printing Objective */
   var_list = &(sys->variable_set);
-  sprintf(print_buf,"MAX-MIN ( ");
-  trace_buf = xbt_realloc(trace_buf,strlen(trace_buf)+strlen(print_buf)+1);
+  sprintf(print_buf, "MAX-MIN ( ");
+  trace_buf =
+      xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
   strcat(trace_buf, print_buf);
   xbt_swag_foreach(var, var_list) {
-    sprintf(print_buf,"'%p'(%f) ",var,var->weight);
-    trace_buf = xbt_realloc(trace_buf,strlen(trace_buf)+strlen(print_buf)+1);
+    sprintf(print_buf, "'%p'(%f) ", var, var->weight);
+    trace_buf =
+	xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
     strcat(trace_buf, print_buf);
   }
-  sprintf(print_buf,")");
-  trace_buf = xbt_realloc(trace_buf,strlen(trace_buf)+strlen(print_buf)+1);
+  sprintf(print_buf, ")");
+  trace_buf =
+      xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
   strcat(trace_buf, print_buf);
-  DEBUG1("%s",trace_buf);
-  trace_buf[0]='\000';
+  DEBUG1("%s", trace_buf);
+  trace_buf[0] = '\000';
 
+  DEBUG0("Constraints");
   /* Printing Constraints */
   cnst_list = &(sys->active_constraint_set);
   xbt_swag_foreach(cnst, cnst_list) {
-    sum=0.0;
+    sum = 0.0;
     elem_list = &(cnst->element_set);
-    sprintf(print_buf,"\t");
-    trace_buf = xbt_realloc(trace_buf,strlen(trace_buf)+strlen(print_buf)+1);
+    sprintf(print_buf, "\t");
+    trace_buf =
+	xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
     strcat(trace_buf, print_buf);
     xbt_swag_foreach(elem, elem_list) {
-      sprintf(print_buf,"%f.'%p'(%f) + ",elem->value, 
-	      elem->variable,elem->variable->value);
-      trace_buf = xbt_realloc(trace_buf,strlen(trace_buf)+strlen(print_buf)+1);
+      sprintf(print_buf, "%f.'%p'(%f) + ", elem->value,
+	      elem->variable, elem->variable->value);
+      trace_buf =
+	  xbt_realloc(trace_buf,
+		      strlen(trace_buf) + strlen(print_buf) + 1);
       strcat(trace_buf, print_buf);
       sum += elem->value * elem->variable->value;
     }
-    sprintf(print_buf,"0 <= %f ('%p')",cnst->bound,cnst);
-    trace_buf = xbt_realloc(trace_buf,strlen(trace_buf)+strlen(print_buf)+1);
+    sprintf(print_buf, "0 <= %f ('%p')", cnst->bound, cnst);
+    trace_buf =
+	xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
     strcat(trace_buf, print_buf);
 
-    if(!cnst->shared) {
-      sprintf(print_buf," [MAX-Constraint]");
-      trace_buf = xbt_realloc(trace_buf,strlen(trace_buf)+strlen(print_buf)+1);
+    if (!cnst->shared) {
+      sprintf(print_buf, " [MAX-Constraint]");
+      trace_buf =
+	  xbt_realloc(trace_buf,
+		      strlen(trace_buf) + strlen(print_buf) + 1);
       strcat(trace_buf, print_buf);
     }
-    DEBUG1("%s",trace_buf);
-    trace_buf[0]='\000';
-    xbt_assert3((sum<=cnst->bound), "Incorrect value (%f is not smaller than %f): %g",
-		sum,cnst->bound,sum-cnst->bound);
+    DEBUG1("%s", trace_buf);
+    trace_buf[0] = '\000';
+    if (double_positive(sum - cnst->bound))
+      WARN3("Incorrect value (%f is not smaller than %f): %g",
+	    sum, cnst->bound, sum - cnst->bound);
   }
 
+  DEBUG0("Variables");
   /* Printing Result */
   xbt_swag_foreach(var, var_list) {
-    if(var->bound>0) {
-      DEBUG4("'%p'(%f) : %f (<=%f)",var,var->weight,var->value, var->bound);
-      xbt_assert0((var->value<=var->bound), "Incorrect value");
-    }
-    else 
-      DEBUG3("'%p'(%f) : %f",var,var->weight,var->value);
+    if (var->bound > 0) {
+      DEBUG4("'%p'(%f) : %f (<=%f)", var, var->weight, var->value,
+	     var->bound);
+      if (double_positive(var->value - var->bound))
+	WARN2("Incorrect value (%f is not smaller than %f",
+	      var->value, var->bound);
+    } else
+      DEBUG3("'%p'(%f) : %f", var, var->weight, var->value);
   }
 
   free(trace_buf);
@@ -420,7 +445,14 @@ void lmm_solve(lmm_system_t sys)
   var_list = &(sys->variable_set);
   DEBUG1("Variable set : %d", xbt_swag_size(var_list));
   xbt_swag_foreach(var, var_list) {
+    int nb=0;
+    int i;
     var->value = 0.0;
+    for (i = 0; i < var->cnsts_number; i++) {
+      if(var->cnsts[i].value==0.0) nb++;
+    }
+    if((nb==var->cnsts_number) && (var->weight>0.0))
+      var->value = 1.0;
   }
 
   /* 
@@ -435,14 +467,14 @@ void lmm_solve(lmm_system_t sys)
     elem_list = &(cnst->element_set);
     cnst->usage = 0.0;
     xbt_swag_foreach(elem, elem_list) {
-      if(elem->variable->weight <=0) break;
+      if (elem->variable->weight <= 0)
+	break;
       if ((elem->value > 0)) {
-	if(cnst->shared)
+	if (cnst->shared)
 	  cnst->usage += elem->value / elem->variable->weight;
-	else 
-	  if(cnst->usage<elem->value / elem->variable->weight)
-	    cnst->usage = elem->value / elem->variable->weight;
-	DEBUG2("Constraint Usage %p : %f",cnst,cnst->usage);
+	else if (cnst->usage < elem->value / elem->variable->weight)
+	  cnst->usage = elem->value / elem->variable->weight;
+	DEBUG2("Constraint Usage %p : %f", cnst, cnst->usage);
 	make_elem_active(elem);
       }
     }
@@ -460,11 +492,13 @@ void lmm_solve(lmm_system_t sys)
     xbt_swag_foreach(var, var_list) {
       /* First check if some of these variables have reach their upper
          bound and update min_usage accordingly. */
-      DEBUG5("var=%p, var->bound=%f, var->weight=%f, min_usage=%f, var->bound*var->weight=%f",
-	     var, var->bound, var->weight, min_usage,var->bound * var->weight);
+      DEBUG5
+	  ("var=%p, var->bound=%f, var->weight=%f, min_usage=%f, var->bound*var->weight=%f",
+	   var, var->bound, var->weight, min_usage,
+	   var->bound * var->weight);
       if ((var->bound > 0) && (var->bound * var->weight < min_usage)) {
 	min_usage = var->bound * var->weight;
-	DEBUG1("Updated min_usage=%f",min_usage);
+	DEBUG1("Updated min_usage=%f", min_usage);
       }
     }
 
@@ -473,7 +507,8 @@ void lmm_solve(lmm_system_t sys)
       int i;
 
       var->value = min_usage / var->weight;
-      DEBUG5("Min usage: %f, Var(%p)->weight: %f, Var(%p)->value: %f ",min_usage,var,var->weight,var,var->value);
+      DEBUG5("Min usage: %f, Var(%p)->weight: %f, Var(%p)->value: %f ",
+	     min_usage, var, var->weight, var, var->value);
 
 
       /* Update usage */
@@ -481,23 +516,25 @@ void lmm_solve(lmm_system_t sys)
       for (i = 0; i < var->cnsts_number; i++) {
 	elem = &var->cnsts[i];
 	cnst = elem->constraint;
-	if(cnst->shared) {
+	if (cnst->shared) {
 	  double_update(&(cnst->remaining), elem->value * var->value);
 	  double_update(&(cnst->usage), elem->value / var->weight);
 	  make_elem_inactive(elem);
-	} else { /* FIXME one day: We recompute usage.... :( */
+	} else {		/* FIXME one day: We recompute usage.... :( */
 	  cnst->usage = 0.0;
 	  make_elem_inactive(elem);
 	  xbt_swag_foreach(elem, elem_list) {
-	    if(elem->variable->weight <=0) break;
-	    if(elem->variable->value > 0) break;
+	    if (elem->variable->weight <= 0)
+	      break;
+	    if (elem->variable->value > 0)
+	      break;
 	    if ((elem->value > 0)) {
-	      if(cnst->usage<elem->value / elem->variable->weight)
+	      if (cnst->usage < elem->value / elem->variable->weight)
 		cnst->usage = elem->value / elem->variable->weight;
-	      DEBUG2("Constraint Usage %p : %f",cnst,cnst->usage);
+	      DEBUG2("Constraint Usage %p : %f", cnst, cnst->usage);
 	      make_elem_active(elem);
 	    }
-	  } 
+	  }
 	}
       }
       xbt_swag_remove(var, var_list);
@@ -514,7 +551,7 @@ void lmm_solve(lmm_system_t sys)
   } while (xbt_swag_size(&(sys->saturated_variable_set)));
 
   sys->modified = 0;
-  if(XBT_LOG_ISENABLED(surf_maxmin, xbt_log_priority_debug)) {
+  if (XBT_LOG_ISENABLED(surf_maxmin, xbt_log_priority_debug)) {
     lmm_print(sys);
   }
 }
@@ -566,7 +603,7 @@ void lmm_update_variable_bound(lmm_system_t sys, lmm_variable_t var,
  *
  */
 void lmm_update_variable_latency(lmm_system_t sys, lmm_variable_t var,
-			       double delta)
+				 double delta)
 {
   sys->modified = 1;
   var->df += delta;
@@ -575,27 +612,30 @@ void lmm_update_variable_latency(lmm_system_t sys, lmm_variable_t var,
 void lmm_update_variable_weight(lmm_system_t sys, lmm_variable_t var,
 				double weight)
 {
-  int i ;
+  int i;
   lmm_element_t elem;
 
-  XBT_IN3("(sys=%p, var=%p, weight=%f)",sys,var,weight);
+  XBT_IN3("(sys=%p, var=%p, weight=%f)", sys, var, weight);
   sys->modified = 1;
   var->weight = weight;
-  xbt_swag_remove(var,&(sys->variable_set));
-  if(weight) xbt_swag_insert_at_head(var,&(sys->variable_set));
-  else xbt_swag_insert_at_tail(var,&(sys->variable_set));
+  xbt_swag_remove(var, &(sys->variable_set));
+  if (weight)
+    xbt_swag_insert_at_head(var, &(sys->variable_set));
+  else
+    xbt_swag_insert_at_tail(var, &(sys->variable_set));
 
   for (i = 0; i < var->cnsts_number; i++) {
     elem = &var->cnsts[i];
     xbt_swag_remove(elem, &(elem->constraint->element_set));
-    if(weight) xbt_swag_insert_at_head(elem, &(elem->constraint->element_set));
-    else xbt_swag_insert_at_tail(elem, &(elem->constraint->element_set));
+    if (weight)
+      xbt_swag_insert_at_head(elem, &(elem->constraint->element_set));
+    else
+      xbt_swag_insert_at_tail(elem, &(elem->constraint->element_set));
   }
   XBT_OUT;
 }
 
 double lmm_get_variable_weight(lmm_variable_t var)
-				  
 {
   return var->weight;
 }
@@ -617,129 +657,8 @@ lmm_constraint_t lmm_get_first_active_constraint(lmm_system_t sys)
   return xbt_swag_getFirst(&(sys->active_constraint_set));
 }
 
-lmm_constraint_t lmm_get_next_active_constraint(lmm_system_t sys, lmm_constraint_t cnst)
+lmm_constraint_t lmm_get_next_active_constraint(lmm_system_t sys,
+						lmm_constraint_t cnst)
 {
-  return xbt_swag_getNext(cnst,(sys->active_constraint_set).offset);
-}
-
-
-
-/** \brief Attribute the value bound to var->bound.
- * 
- *  \param func_f    default function f associated with the chosen protocol flavor
- *  \param func_fp   partial differential of f (f prime, f')
- *  \param func_fpi  inverse of the partial differential of f (f prime inverse, (f')^{-1})
- *  \param func_fpip partial differential of the inverse of the partial differential of f (f prime inverse prime, ((f')^{-1})')
- * 
- *  Set default functions to the ones passed as parameters. This is a polimorfism in C pure, enjoy the roots of programming.
- *
- */
-void lmm_set_default_protocol_functions(double (* func_f)    (lmm_variable_t var, double x),
-					double (* func_fp)   (lmm_variable_t var, double x),
-					double (* func_fpi)  (lmm_variable_t var, double x),
-					double (* func_fpip) (lmm_variable_t var, double x))
-					
-{
-  func_f_def    = func_f;
-  func_fp_def   = func_fp;
-  func_fpi_def  = func_fpi;
-  func_fpip_def = func_fpip;
-}
-
-
-/*
- * NOTE for Reno: all functions consider the network
- * coeficient (alpha) equal to 1.
- */
-
-/*
- * For Vegas f: $\alpha_f d_f \log\left(x_f\right)$
- */
-double func_vegas_f(lmm_variable_t var, double x){
-  return var->df * log(x);
-}
-
-/*
- * For Vegas fp: $\frac{\alpha D_f}{x}$
- */
-double func_vegas_fp(lmm_variable_t var, double x){
-  //avoid a disaster value - c'est du bricolage mais ca marche
-  if(x == 0) x = 10e-8;
-  return var->df/x;
-}
-
-/*
- * For Vegas fpi: $\frac{\alpha D_f}{x}$
- */
-double func_vegas_fpi(lmm_variable_t var, double x){
-  //avoid a disaster value - c'est du bricolage mais ca marche
-  if(x == 0) x = 10e-8;
-  return var->df/x;
-}
-
-/*
- * For Vegas fpip: $-\frac{\alpha D_f}{x^2}$
- */
-double func_vegas_fpip(lmm_variable_t var, double x){
-  //avoid a disaster value - c'est du bricolage mais ca marche
-  if(x == 0) x = 10e-8;
-  return -( var->df/(x*x) ) ;
-}
-
-
-/*
- * For Reno f: $\frac{\sqrt{\frac{3}{2}}}{D_f} \arctan\left(\sqrt{\frac{3}{2}}x_f D_f\right)$
- */
-double func_reno_f(lmm_variable_t var, double x){
-  xbt_assert0( var->df, "Please report this bug.");
-  // \sqrt{3/2} = 0.8164965808
-  return (0.8164965808 / var->df) * atan( (0.8164965808 / var->df)*x );
-}
-
-/*
- * For Reno fp: $\frac{3}{3 {D_f}^2 x^2 + 2}$
- */
-double func_reno_fp(lmm_variable_t var, double x){
-  return 3 / (3*var->df*var->df*x*x + 2);
-}
-
-/*
- * For Reno fpi: $\sqrt{\frac{1}{{D_f}^2 x} - \frac{2}{3{D_f}^2}}$
- */
-double func_reno_fpi(lmm_variable_t var, double x){
-  double res_fpi; 
-  xbt_assert0( var->df, "Please report this bug.");
-
-  //avoid a disaster value - c'est du bricolage mais ca marche
-  if(x == 0) x = 10e-8;
- 
-  res_fpi = 1/(var->df*var->df*x) - 2/(3*var->df*var->df);
-
-  //avoid a disaster value of res_fpi
-  if(res_fpi < 0.0) return 0.0;
-  else return sqrt(res_fpi);
-}
-
-/*
- * For Reno fpip:  $-\frac{1}{2 {D_f}^2 x^2\sqrt{\frac{1}{{D_f}^2 x} - \frac{2}{3{D_f}^2}}}$
- */
-double func_reno_fpip(lmm_variable_t var, double x){
-  double res_fpip; 
-  double critical_test;
-
-  xbt_assert0(var->df,"Please report this bug.");
-
-  //avoid division by zero - c'est du bricolage mais ca marche
-  if(x == 0) x = 10e-8;
-
-  res_fpip = 1/(var->df*var->df*x) - 2/(3*var->df*var->df);
-  
-  //avoid square root of negative number
-  if(res_fpip < 0.0) return 0.0;
-
-  //avoid division by zero
-  critical_test = (2*var->df*var->df*x*x*sqrt(res_fpip));
-
-  if(critical_test == 0.0) return 0.0;
-  else return -(1/critical_test);
+  return xbt_swag_getNext(cnst, (sys->active_constraint_set).offset);
 }