src/surf/maxmin.c

   1 /*      $Id$     */
   2
   3 /* Copyright (c) 2004 Arnaud Legrand. All rights reserved.                  */
   4
   5 /* This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the license (GNU LGPL) which comes with this package. */
   7
   8
   9 #include "xbt/sysdep.h"
  10 #include "xbt/log.h"
  11 #include "xbt/mallocator.h"
  12 #include "maxmin_private.h"
  13 #include <stdlib.h>
  14 #include <math.h>
  15 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(surf_maxmin, surf,
  16                                 "Logging specific to SURF (maxmin)");
  17
  18 static void* lmm_variable_mallocator_new_f(void);
  19 static void lmm_variable_mallocator_free_f(void *var);
  20 static void lmm_variable_mallocator_reset_f(void *var);
  21
  22 lmm_system_t lmm_system_new(void)
  23 {
  24   lmm_system_t l = NULL;
  25   s_lmm_variable_t var;
  26   s_lmm_constraint_t cnst;
  27
  28   l = xbt_new0(s_lmm_system_t, 1);
  29
  30   l->modified = 0;
  31   xbt_swag_init(&(l->variable_set),
  32                 xbt_swag_offset(var, variable_set_hookup));
  33   xbt_swag_init(&(l->constraint_set),
  34                 xbt_swag_offset(cnst, constraint_set_hookup));
  35
  36   xbt_swag_init(&(l->active_constraint_set),
  37                 xbt_swag_offset(cnst, active_constraint_set_hookup));
  38
  39   xbt_swag_init(&(l->saturated_variable_set),
  40                 xbt_swag_offset(var, saturated_variable_set_hookup));
  41   xbt_swag_init(&(l->saturated_constraint_set),
  42                 xbt_swag_offset(cnst, saturated_constraint_set_hookup));
  43
  44   l->variable_mallocator = xbt_mallocator_new(64,
  45                                               lmm_variable_mallocator_new_f,
  46                                               lmm_variable_mallocator_free_f,
  47                                               lmm_variable_mallocator_reset_f);
  48
  49   return l;
  50 }
  51
  52 void lmm_system_free(lmm_system_t sys)
  53 {
  54   lmm_variable_t var = NULL;
  55   lmm_constraint_t cnst = NULL;
  56
  57   while ((var = extract_variable(sys)))
  58     lmm_var_free(sys, var);
  59
  60   while ((cnst = extract_constraint(sys)))
  61     lmm_cnst_free(sys, cnst);
  62
  63   xbt_mallocator_free(sys->variable_mallocator);
  64   free(sys);
  65 }
  66
  67 void lmm_variable_disable(lmm_system_t sys, lmm_variable_t var)
  68 {
  69   int i;
  70   lmm_element_t elem = NULL;
  71
  72   XBT_IN2("(sys=%p, var=%p)",sys,var);
  73   sys->modified = 1;
  74
  75   for (i = 0; i < var->cnsts_number; i++) {
  76     elem = &var->cnsts[i];
  77     xbt_swag_remove(elem, &(elem->constraint->element_set));
  78     xbt_swag_remove(elem, &(elem->constraint->active_element_set));
  79     if (!xbt_swag_size(&(elem->constraint->element_set)))
  80       make_constraint_inactive(sys, elem->constraint);
  81   }
  82   var->cnsts_number = 0;
  83   XBT_OUT;
  84 }
  85
  86 static void lmm_var_free(lmm_system_t sys, lmm_variable_t var)
  87 {
  88
  89   lmm_variable_disable(sys, var);
  90   free(var->cnsts);
  91   xbt_mallocator_release(sys->variable_mallocator, var);
  92 }
  93
  94 static void lmm_cnst_free(lmm_system_t sys, lmm_constraint_t cnst)
  95 {
  96 /*   xbt_assert0(xbt_swag_size(&(cnst->element_set)), */
  97 /*            "This list should be empty!"); */
  98   remove_active_constraint(sys, cnst);
  99   free(cnst);
 100 }
 101
 102 lmm_constraint_t lmm_constraint_new(lmm_system_t sys, void *id,
 103                                     double bound_value)
 104 {
 105   lmm_constraint_t cnst = NULL;
 106   s_lmm_element_t elem;
 107
 108   cnst = xbt_new0(s_lmm_constraint_t, 1);
 109   cnst->id = id;
 110   xbt_swag_init(&(cnst->element_set),
 111                 xbt_swag_offset(elem, element_set_hookup));
 112   xbt_swag_init(&(cnst->active_element_set),
 113                 xbt_swag_offset(elem, active_element_set_hookup));
 114
 115   cnst->bound = bound_value;
 116   cnst->usage = 0;
 117   cnst->shared = 1;
 118   insert_constraint(sys, cnst);
 119
 120   return cnst;
 121 }
 122
 123 void lmm_constraint_shared(lmm_constraint_t cnst)
 124 {
 125   cnst->shared = 0;
 126 }
 127
 128 void lmm_constraint_free(lmm_system_t sys, lmm_constraint_t cnst)
 129 {
 130   remove_constraint(sys, cnst);
 131   lmm_cnst_free(sys, cnst);
 132 }
 133
 134 static void* lmm_variable_mallocator_new_f(void) {
 135   return xbt_new(s_lmm_variable_t, 1);
 136 }
 137
 138 static void lmm_variable_mallocator_free_f(void *var) {
 139   xbt_free(var);
 140 }
 141
 142 static void lmm_variable_mallocator_reset_f(void *var) {
 143   /* memset to zero like calloc */
 144   memset(var, 0, sizeof(s_lmm_variable_t));
 145 }
 146
 147 lmm_variable_t lmm_variable_new(lmm_system_t sys, void *id,
 148                                 double weight,
 149                                 double bound, int number_of_constraints)
 150 {
 151   lmm_variable_t var = NULL;
 152   int i;
 153
 154   XBT_IN5("(sys=%p, id=%p, weight=%f, bound=%f, num_cons =%d)",
 155           sys,id,weight,bound,number_of_constraints);
 156
 157   var = xbt_mallocator_get(sys->variable_mallocator);
 158   var->id = id;
 159   var->cnsts = xbt_new0(s_lmm_element_t, number_of_constraints);
 160   for(i=0; i<number_of_constraints; i++) {
 161     /* Should be useless because of the
 162        calloc but it seems to help valgrind... */
 163     var->cnsts[i].element_set_hookup.next = NULL;
 164     var->cnsts[i].element_set_hookup.prev = NULL;
 165     var->cnsts[i].active_element_set_hookup.next = NULL;
 166     var->cnsts[i].active_element_set_hookup.prev = NULL;
 167     var->cnsts[i].constraint = NULL;
 168     var->cnsts[i].variable = NULL;
 169     var->cnsts[i].value = 0.0;
 170   }
 171   var->cnsts_size = number_of_constraints;
 172   var->cnsts_number = 0; /* Should be useless because of the
 173                             calloc but it seems to help valgrind... */
 174   var->weight = weight;
 175   var->bound = bound;
 176   var->value = 0.0;
 177   var->df    = 0.0;
 178
 179   var->func_f    = func_f_def;
 180   var->func_fp   = func_fp_def;
 181   var->func_fpi  = func_fpi_def;
 182   var->func_fpip = func_fpip_def;
 183
 184   if(weight) xbt_swag_insert_at_head(var,&(sys->variable_set));
 185   else xbt_swag_insert_at_tail(var,&(sys->variable_set));
 186   XBT_OUT;
 187   return var;
 188 }
 189
 190 void lmm_variable_free(lmm_system_t sys, lmm_variable_t var)
 191 {
 192   remove_variable(sys, var);
 193   lmm_var_free(sys, var);
 194 }
 195
 196 double lmm_variable_getvalue(lmm_variable_t var)
 197 {
 198   return (var->value);
 199 }
 200
 201 void lmm_expand(lmm_system_t sys, lmm_constraint_t cnst,
 202                 lmm_variable_t var, double value)
 203 {
 204   lmm_element_t elem = NULL;
 205
 206   sys->modified = 1;
 207
 208   xbt_assert0(var->cnsts_number < var->cnsts_size,
 209               "Too much constraints");
 210
 211   elem = &(var->cnsts[var->cnsts_number++]);
 212
 213   elem->value = value;
 214   elem->constraint = cnst;
 215   elem->variable = var;
 216
 217   if(var->weight) xbt_swag_insert_at_head(elem,&(elem->constraint->element_set));
 218   else xbt_swag_insert_at_tail(elem,&(elem->constraint->element_set));
 219
 220   make_constraint_active(sys, cnst);
 221 }
 222
 223 void lmm_expand_add(lmm_system_t sys, lmm_constraint_t cnst,
 224                     lmm_variable_t var, double value)
 225 {
 226   int i ;
 227   sys->modified = 1;
 228
 229   for(i=0; i< var->cnsts_number ; i++)
 230     if(var->cnsts[i].constraint == cnst) break;
 231
 232   if(i<var->cnsts_number) var->cnsts[i].value +=value;
 233   else lmm_expand(sys,cnst,var,value);
 234 }
 235
 236 void lmm_elem_set_value(lmm_system_t sys, lmm_constraint_t cnst,
 237                         lmm_variable_t var, double value)
 238 {
 239   int i ;
 240
 241   for(i=0; i< var->cnsts_number ; i++)
 242     if(var->cnsts[i].constraint == cnst) break;
 243
 244   if(i<var->cnsts_number) {
 245     var->cnsts[i].value =value;
 246     sys->modified = 1;
 247   } else DIE_IMPOSSIBLE;
 248 }
 249
 250 lmm_constraint_t lmm_get_cnst_from_var(lmm_system_t sys,
 251                                        lmm_variable_t var, int num)
 252 {
 253   if (num < var->cnsts_number)
 254     return (var->cnsts[num].constraint);
 255   else
 256     return NULL;
 257 }
 258
 259 int lmm_get_number_of_cnst_from_var(lmm_system_t sys, lmm_variable_t var)
 260 {
 261   return (var->cnsts_number);
 262 }
 263
 264 lmm_variable_t lmm_get_var_from_cnst(lmm_system_t sys,
 265                                      lmm_constraint_t cnst,
 266                                      lmm_variable_t * var)
 267 {
 268   if (!(*var))
 269     xbt_swag_getFirst(&(cnst->element_set));
 270   else
 271     *var = xbt_swag_getNext(*var, cnst->element_set.offset);
 272   return *var;
 273 }
 274
 275 void *lmm_constraint_id(lmm_constraint_t cnst)
 276 {
 277   return cnst->id;
 278 }
 279
 280 void *lmm_variable_id(lmm_variable_t var)
 281 {
 282   return var->id;
 283 }
 284
 285 static void saturated_constraint_set_update(lmm_system_t sys,
 286                                             lmm_constraint_t cnst,
 287                                             double *min_usage)
 288 {
 289   lmm_constraint_t useless_cnst = NULL;
 290
 291   XBT_IN3("sys=%p, cnst=%p, min_usage=%f",sys,cnst,*min_usage);
 292   if (cnst->usage <= 0) {
 293     XBT_OUT;
 294     return;
 295   }
 296   if (cnst->remaining <= 0) {
 297     XBT_OUT;
 298     return;
 299   }
 300   if ((*min_usage < 0) || (*min_usage > cnst->remaining / cnst->usage)) {
 301     *min_usage = cnst->remaining / cnst->usage;
 302     LOG3(xbt_log_priority_trace,
 303          "min_usage=%f (cnst->remaining=%f, cnst->usage=%f)",*min_usage,
 304          cnst->remaining, cnst->usage);
 305     while ((useless_cnst =
 306             xbt_swag_getFirst(&(sys->saturated_constraint_set))))
 307       xbt_swag_remove(useless_cnst, &(sys->saturated_constraint_set));
 308
 309     xbt_swag_insert(cnst, &(sys->saturated_constraint_set));
 310   } else if (*min_usage == cnst->remaining / cnst->usage) {
 311     xbt_swag_insert(cnst, &(sys->saturated_constraint_set));
 312   }
 313   XBT_OUT;
 314 }
 315
 316 static void saturated_variable_set_update(lmm_system_t sys)
 317 {
 318   lmm_constraint_t cnst = NULL;
 319   xbt_swag_t cnst_list = NULL;
 320   lmm_element_t elem = NULL;
 321   xbt_swag_t elem_list = NULL;
 322
 323   cnst_list = &(sys->saturated_constraint_set);
 324   while ((cnst = xbt_swag_getFirst(cnst_list))) {
 325     elem_list = &(cnst->active_element_set);
 326     xbt_swag_foreach(elem, elem_list) {
 327       if(elem->variable->weight<=0) break;
 328       if ((elem->value > 0))
 329         xbt_swag_insert(elem->variable, &(sys->saturated_variable_set));
 330     }
 331     xbt_swag_remove(cnst, cnst_list);
 332   }
 333 }
 334
 335 void lmm_print(lmm_system_t sys)
 336
 337 {
 338   lmm_constraint_t cnst = NULL;
 339   lmm_element_t elem = NULL;
 340   lmm_variable_t var = NULL;
 341   xbt_swag_t cnst_list = NULL;
 342   xbt_swag_t var_list = NULL;
 343   xbt_swag_t elem_list = NULL;
 344   char print_buf[1024];
 345   char *trace_buf=xbt_malloc0(sizeof(char));
 346   double sum=0.0;
 347
 348   /* Printing Objective */
 349   var_list = &(sys->variable_set);
 350   sprintf(print_buf,"MAX-MIN ( ");
 351   trace_buf = xbt_realloc(trace_buf,strlen(trace_buf)+strlen(print_buf)+1);
 352   strcat(trace_buf, print_buf);
 353   xbt_swag_foreach(var, var_list) {
 354     sprintf(print_buf,"'%p'(%f) ",var,var->weight);
 355     trace_buf = xbt_realloc(trace_buf,strlen(trace_buf)+strlen(print_buf)+1);
 356     strcat(trace_buf, print_buf);
 357   }
 358   sprintf(print_buf,")");
 359   trace_buf = xbt_realloc(trace_buf,strlen(trace_buf)+strlen(print_buf)+1);
 360   strcat(trace_buf, print_buf);
 361   DEBUG1("%s",trace_buf);
 362   trace_buf[0]='\000';
 363
 364   /* Printing Constraints */
 365   cnst_list = &(sys->active_constraint_set);
 366   xbt_swag_foreach(cnst, cnst_list) {
 367     sum=0.0;
 368     elem_list = &(cnst->element_set);
 369     sprintf(print_buf,"\t");
 370     trace_buf = xbt_realloc(trace_buf,strlen(trace_buf)+strlen(print_buf)+1);
 371     strcat(trace_buf, print_buf);
 372     xbt_swag_foreach(elem, elem_list) {
 373       sprintf(print_buf,"%f.'%p'(%f) + ",elem->value,
 374               elem->variable,elem->variable->value);
 375       trace_buf = xbt_realloc(trace_buf,strlen(trace_buf)+strlen(print_buf)+1);
 376       strcat(trace_buf, print_buf);
 377       sum += elem->value * elem->variable->value;
 378     }
 379     sprintf(print_buf,"0 <= %f ('%p')",cnst->bound,cnst);
 380     trace_buf = xbt_realloc(trace_buf,strlen(trace_buf)+strlen(print_buf)+1);
 381     strcat(trace_buf, print_buf);
 382
 383     if(!cnst->shared) {
 384       sprintf(print_buf," [MAX-Constraint]");
 385       trace_buf = xbt_realloc(trace_buf,strlen(trace_buf)+strlen(print_buf)+1);
 386       strcat(trace_buf, print_buf);
 387     }
 388     DEBUG1("%s",trace_buf);
 389     trace_buf[0]='\000';
 390     xbt_assert3(!double_positive(sum-cnst->bound), "Incorrect value (%f is not smaller than %f): %g",
 391                 sum,cnst->bound,sum-cnst->bound);
 392   }
 393
 394   /* Printing Result */
 395   xbt_swag_foreach(var, var_list) {
 396     if(var->bound>0) {
 397       DEBUG4("'%p'(%f) : %f (<=%f)",var,var->weight,var->value, var->bound);
 398       xbt_assert2(!double_positive(var->value-var->bound), "Incorrect value (%f is not smaller than %f",
 399                   var->value, var->bound);
 400     }
 401     else
 402       DEBUG3("'%p'(%f) : %f",var,var->weight,var->value);
 403   }
 404
 405   free(trace_buf);
 406 }
 407
 408 void lmm_solve(lmm_system_t sys)
 409 {
 410   lmm_variable_t var = NULL;
 411   lmm_constraint_t cnst = NULL;
 412   lmm_element_t elem = NULL;
 413   xbt_swag_t cnst_list = NULL;
 414   xbt_swag_t var_list = NULL;
 415   xbt_swag_t elem_list = NULL;
 416   double min_usage = -1;
 417
 418   if (!(sys->modified))
 419     return;
 420
 421   /* Init */
 422   var_list = &(sys->variable_set);
 423   DEBUG1("Variable set : %d", xbt_swag_size(var_list));
 424   xbt_swag_foreach(var, var_list) {
 425     var->value = 0.0;
 426   }
 427
 428   /*
 429    * Compute Usage and store the variables that reach the maximum.
 430    */
 431   cnst_list = &(sys->active_constraint_set);
 432   DEBUG1("Active constraints : %d", xbt_swag_size(cnst_list));
 433   xbt_swag_foreach(cnst, cnst_list) {
 434     /* INIT */
 435     cnst->remaining = cnst->bound;
 436     cnst->usage = 0;
 437     elem_list = &(cnst->element_set);
 438     cnst->usage = 0.0;
 439     xbt_swag_foreach(elem, elem_list) {
 440       if(elem->variable->weight <=0) break;
 441       if ((elem->value > 0)) {
 442         if(cnst->shared)
 443           cnst->usage += elem->value / elem->variable->weight;
 444         else
 445           if(cnst->usage<elem->value / elem->variable->weight)
 446             cnst->usage = elem->value / elem->variable->weight;
 447         DEBUG2("Constraint Usage %p : %f",cnst,cnst->usage);
 448         make_elem_active(elem);
 449       }
 450     }
 451     /* Saturated constraints update */
 452     saturated_constraint_set_update(sys, cnst, &min_usage);
 453   }
 454   saturated_variable_set_update(sys);
 455
 456   /* Saturated variables update */
 457
 458   do {
 459     /* Fix the variables that have to be */
 460     var_list = &(sys->saturated_variable_set);
 461
 462     xbt_swag_foreach(var, var_list) {
 463       /* First check if some of these variables have reach their upper
 464          bound and update min_usage accordingly. */
 465       DEBUG5("var=%p, var->bound=%f, var->weight=%f, min_usage=%f, var->bound*var->weight=%f",
 466              var, var->bound, var->weight, min_usage,var->bound * var->weight);
 467       if ((var->bound > 0) && (var->bound * var->weight < min_usage)) {
 468         min_usage = var->bound * var->weight;
 469         DEBUG1("Updated min_usage=%f",min_usage);
 470       }
 471     }
 472
 473
 474     while ((var = xbt_swag_getFirst(var_list))) {
 475       int i;
 476
 477       var->value = min_usage / var->weight;
 478       DEBUG5("Min usage: %f, Var(%p)->weight: %f, Var(%p)->value: %f ",min_usage,var,var->weight,var,var->value);
 479
 480
 481       /* Update usage */
 482
 483       for (i = 0; i < var->cnsts_number; i++) {
 484         elem = &var->cnsts[i];
 485         cnst = elem->constraint;
 486         if(cnst->shared) {
 487           double_update(&(cnst->remaining), elem->value * var->value);
 488           double_update(&(cnst->usage), elem->value / var->weight);
 489           make_elem_inactive(elem);
 490         } else { /* FIXME one day: We recompute usage.... :( */
 491           cnst->usage = 0.0;
 492           make_elem_inactive(elem);
 493           xbt_swag_foreach(elem, elem_list) {
 494             if(elem->variable->weight <=0) break;
 495             if(elem->variable->value > 0) break;
 496             if ((elem->value > 0)) {
 497               if(cnst->usage<elem->value / elem->variable->weight)
 498                 cnst->usage = elem->value / elem->variable->weight;
 499               DEBUG2("Constraint Usage %p : %f",cnst,cnst->usage);
 500               make_elem_active(elem);
 501             }
 502           }
 503         }
 504       }
 505       xbt_swag_remove(var, var_list);
 506     }
 507
 508     /* Find out which variables reach the maximum */
 509     cnst_list = &(sys->active_constraint_set);
 510     min_usage = -1;
 511     xbt_swag_foreach(cnst, cnst_list) {
 512       saturated_constraint_set_update(sys, cnst, &min_usage);
 513     }
 514     saturated_variable_set_update(sys);
 515
 516   } while (xbt_swag_size(&(sys->saturated_variable_set)));
 517
 518   sys->modified = 0;
 519   if(XBT_LOG_ISENABLED(surf_maxmin, xbt_log_priority_debug)) {
 520     lmm_print(sys);
 521   }
 522 }
 523
 524 /* Not a O(1) function */
 525
 526 void lmm_update(lmm_system_t sys, lmm_constraint_t cnst,
 527                 lmm_variable_t var, double value)
 528 {
 529   int i;
 530
 531   sys->modified = 1;
 532   for (i = 0; i < var->cnsts_number; i++)
 533     if (var->cnsts[i].constraint == cnst) {
 534       var->cnsts[i].value = value;
 535       return;
 536     }
 537 }
 538
 539 /** \brief Attribute the value bound to var->bound.
 540  *
 541  *  \param sys the lmm_system_t
 542  *  \param var the lmm_variable_t
 543  *  \param bound the new bound to associate with var
 544  *
 545  *  Makes var->bound equal to bound. Whenever this function is called
 546  *  a change is  signed in the system. To
 547  *  avoid false system changing detection it is a good idea to test
 548  *  (bound != 0) before calling it.
 549  *
 550  */
 551 void lmm_update_variable_bound(lmm_system_t sys, lmm_variable_t var,
 552                                double bound)
 553 {
 554   sys->modified = 1;
 555   var->bound = bound;
 556 }
 557
 558 /** \brief Add the value delta to var->df (the sum of latencies).
 559  *
 560  *  \param sys the lmm_system_t associated
 561  *  \param var the lmm_variable_t which need to updated
 562  *  \param delta the variation of the latency
 563  *
 564  *  Add the value delta to var->df (the sum of latencys associated to the
 565  *  flow). Whenever this function is called a change is  signed in the system. To
 566  *  avoid false system changing detection it is a good idea to test
 567  *  (delta != 0) before calling it.
 568  *
 569  */
 570 void lmm_update_variable_latency(lmm_system_t sys, lmm_variable_t var,
 571                                double delta)
 572 {
 573   sys->modified = 1;
 574   var->df += delta;
 575 }
 576
 577 void lmm_update_variable_weight(lmm_system_t sys, lmm_variable_t var,
 578                                 double weight)
 579 {
 580   int i ;
 581   lmm_element_t elem;
 582
 583   XBT_IN3("(sys=%p, var=%p, weight=%f)",sys,var,weight);
 584   sys->modified = 1;
 585   var->weight = weight;
 586   xbt_swag_remove(var,&(sys->variable_set));
 587   if(weight) xbt_swag_insert_at_head(var,&(sys->variable_set));
 588   else xbt_swag_insert_at_tail(var,&(sys->variable_set));
 589
 590   for (i = 0; i < var->cnsts_number; i++) {
 591     elem = &var->cnsts[i];
 592     xbt_swag_remove(elem, &(elem->constraint->element_set));
 593     if(weight) xbt_swag_insert_at_head(elem, &(elem->constraint->element_set));
 594     else xbt_swag_insert_at_tail(elem, &(elem->constraint->element_set));
 595   }
 596   XBT_OUT;
 597 }
 598
 599 double lmm_get_variable_weight(lmm_variable_t var)
 600
 601 {
 602   return var->weight;
 603 }
 604
 605 void lmm_update_constraint_bound(lmm_system_t sys, lmm_constraint_t cnst,
 606                                  double bound)
 607 {
 608   sys->modified = 1;
 609   cnst->bound = bound;
 610 }
 611
 612 int lmm_constraint_used(lmm_system_t sys, lmm_constraint_t cnst)
 613 {
 614   return xbt_swag_belongs(cnst, &(sys->active_constraint_set));
 615 }
 616
 617 lmm_constraint_t lmm_get_first_active_constraint(lmm_system_t sys)
 618 {
 619   return xbt_swag_getFirst(&(sys->active_constraint_set));
 620 }
 621
 622 lmm_constraint_t lmm_get_next_active_constraint(lmm_system_t sys, lmm_constraint_t cnst)
 623 {
 624   return xbt_swag_getNext(cnst,(sys->active_constraint_set).offset);
 625 }
 626
 627
 628
 629 /** \brief Attribute the value bound to var->bound.
 630  *
 631  *  \param func_f    default function f associated with the chosen protocol flavor
 632  *  \param func_fp   partial differential of f (f prime, f')
 633  *  \param func_fpi  inverse of the partial differential of f (f prime inverse, (f')^{-1})
 634  *  \param func_fpip partial differential of the inverse of the partial differential of f (f prime inverse prime, ((f')^{-1})')
 635  *
 636  *  Set default functions to the ones passed as parameters. This is a polimorfism in C pure, enjoy the roots of programming.
 637  *
 638  */
 639 void lmm_set_default_protocol_functions(double (* func_fpi)  (lmm_variable_t var, double x))
 640 {
 641   func_fpi_def  = func_fpi;
 642 }
 643