alpar@9: /* glpnet04.c (grid-like network problem generator) */
alpar@9: 
alpar@9: /***********************************************************************
alpar@9: *  This code is part of GLPK (GNU Linear Programming Kit).
alpar@9: *
alpar@9: *  This code is a modified version of the program GRIDGEN, a grid-like
alpar@9: *  network problem generator developed by Yusin Lee and Jim Orlin.
alpar@9: *  The original code is publically available on the DIMACS ftp site at:
alpar@9: *  <ftp://dimacs.rutgers.edu/pub/netflow/generators/network/gridgen>.
alpar@9: *
alpar@9: *  All changes concern only the program interface, so this modified
alpar@9: *  version produces exactly the same instances as the original version.
alpar@9: *
alpar@9: *  Changes were made by Andrew Makhorin <mao@gnu.org>.
alpar@9: *
alpar@9: *  GLPK is free software: you can redistribute it and/or modify it
alpar@9: *  under the terms of the GNU General Public License as published by
alpar@9: *  the Free Software Foundation, either version 3 of the License, or
alpar@9: *  (at your option) any later version.
alpar@9: *
alpar@9: *  GLPK is distributed in the hope that it will be useful, but WITHOUT
alpar@9: *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
alpar@9: *  or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
alpar@9: *  License for more details.
alpar@9: *
alpar@9: *  You should have received a copy of the GNU General Public License
alpar@9: *  along with GLPK. If not, see <http://www.gnu.org/licenses/>.
alpar@9: ***********************************************************************/
alpar@9: 
alpar@9: #include "glpapi.h"
alpar@9: 
alpar@9: /***********************************************************************
alpar@9: *  NAME
alpar@9: *
alpar@9: *  glp_gridgen - grid-like network problem generator
alpar@9: *
alpar@9: *  SYNOPSIS
alpar@9: *
alpar@9: *  int glp_gridgen(glp_graph *G, int v_rhs, int a_cap, int a_cost,
alpar@9: *     const int parm[1+14]);
alpar@9: *
alpar@9: *  DESCRIPTION
alpar@9: *
alpar@9: *  The routine glp_gridgen is a grid-like network problem generator
alpar@9: *  developed by Yusin Lee and Jim Orlin.
alpar@9: *
alpar@9: *  The parameter G specifies the graph object, to which the generated
alpar@9: *  problem data have to be stored. Note that on entry the graph object
alpar@9: *  is erased with the routine glp_erase_graph.
alpar@9: *
alpar@9: *  The parameter v_rhs specifies an offset of the field of type double
alpar@9: *  in the vertex data block, to which the routine stores the supply or
alpar@9: *  demand value. If v_rhs < 0, the value is not stored.
alpar@9: *
alpar@9: *  The parameter a_cap specifies an offset of the field of type double
alpar@9: *  in the arc data block, to which the routine stores the arc capacity.
alpar@9: *  If a_cap < 0, the capacity is not stored.
alpar@9: *
alpar@9: *  The parameter a_cost specifies an offset of the field of type double
alpar@9: *  in the arc data block, to which the routine stores the per-unit cost
alpar@9: *  if the arc flow. If a_cost < 0, the cost is not stored.
alpar@9: *
alpar@9: *  The array parm contains description of the network to be generated:
alpar@9: *
alpar@9: *  parm[0]  not used
alpar@9: *  parm[1]  two-ways arcs indicator:
alpar@9: *           1 - if links in both direction should be generated
alpar@9: *           0 - otherwise
alpar@9: *  parm[2]  random number seed (a positive integer)
alpar@9: *  parm[3]  number of nodes (the number of nodes generated might be
alpar@9: *           slightly different to make the network a grid)
alpar@9: *  parm[4]  grid width
alpar@9: *  parm[5]  number of sources
alpar@9: *  parm[6]  number of sinks
alpar@9: *  parm[7]  average degree
alpar@9: *  parm[8]  total flow
alpar@9: *  parm[9]  distribution of arc costs:
alpar@9: *           1 - uniform
alpar@9: *           2 - exponential
alpar@9: *  parm[10] lower bound for arc cost (uniform)
alpar@9: *           100 * lambda (exponential)
alpar@9: *  parm[11] upper bound for arc cost (uniform)
alpar@9: *           not used (exponential)
alpar@9: *  parm[12] distribution of arc capacities:
alpar@9: *           1 - uniform
alpar@9: *           2 - exponential
alpar@9: *  parm[13] lower bound for arc capacity (uniform)
alpar@9: *           100 * lambda (exponential)
alpar@9: *  parm[14] upper bound for arc capacity (uniform)
alpar@9: *           not used (exponential)
alpar@9: *
alpar@9: *  RETURNS
alpar@9: *
alpar@9: *  If the instance was successfully generated, the routine glp_gridgen
alpar@9: *  returns zero; otherwise, if specified parameters are inconsistent,
alpar@9: *  the routine returns a non-zero error code.
alpar@9: *
alpar@9: *  COMMENTS
alpar@9: *
alpar@9: *  This network generator generates a grid-like network plus a super
alpar@9: *  node. In additional to the arcs connecting the nodes in the grid,
alpar@9: *  there is an arc from each supply node to the super node and from the
alpar@9: *  super node to each demand node to guarantee feasiblity. These arcs
alpar@9: *  have very high costs and very big capacities.
alpar@9: *
alpar@9: *  The idea of this network generator is as follows: First, a grid of
alpar@9: *  n1 * n2 is generated. For example, 5 * 3. The nodes are numbered as
alpar@9: *  1 to 15, and the supernode is numbered as n1*n2+1. Then arcs between
alpar@9: *  adjacent nodes are generated. For these arcs, the user is allowed to
alpar@9: *  specify either to generate two-way arcs or one-way arcs. If two-way
alpar@9: *  arcs are to be generated, two arcs, one in each direction, will be
alpar@9: *  generated between each adjacent node pairs. Otherwise, only one arc
alpar@9: *  will be generated. If this is the case, the arcs will be generated
alpar@9: *  in alterntive directions as shown below.
alpar@9: *
alpar@9: *      1 ---> 2 ---> 3 ---> 4 ---> 5
alpar@9: *      |      ^      |      ^      |
alpar@9: *      |      |      |      |      |
alpar@9: *      V      |      V      |      V
alpar@9: *      6 <--- 7 <--- 8 <--- 9 <--- 10
alpar@9: *      |      ^      |      ^      |
alpar@9: *      |      |      |      |      |
alpar@9: *      V      |      V      |      V
alpar@9: *     11 --->12 --->13 --->14 ---> 15
alpar@9: *
alpar@9: *  Then the arcs between the super node and the source/sink nodes are
alpar@9: *  added as mentioned before. If the number of arcs still doesn't reach
alpar@9: *  the requirement, additional arcs will be added by uniformly picking
alpar@9: *  random node pairs. There is no checking to prevent multiple arcs
alpar@9: *  between any pair of nodes. However, there will be no self-arcs (arcs
alpar@9: *  that poins back to its tail node) in the network.
alpar@9: *
alpar@9: *  The source and sink nodes are selected uniformly in the network, and
alpar@9: *  the imbalances of each source/sink node are also assigned by uniform
alpar@9: *  distribution. */
alpar@9: 
alpar@9: struct stat_para
alpar@9: {     /* structure for statistical distributions */
alpar@9:       int distribution;
alpar@9:       /* the distribution: */
alpar@9: #define UNIFORM      1  /* uniform distribution */
alpar@9: #define EXPONENTIAL  2  /* exponential distribution */
alpar@9:       double parameter[5];
alpar@9:       /* the parameters of the distribution */
alpar@9: };
alpar@9: 
alpar@9: struct arcs
alpar@9: {     int from;
alpar@9:       /* the FROM node of that arc */
alpar@9:       int to;
alpar@9:       /* the TO node of that arc */
alpar@9:       int cost;
alpar@9:       /* original cost of that arc */
alpar@9:       int u;
alpar@9:       /* capacity of the arc */
alpar@9: };
alpar@9: 
alpar@9: struct imbalance
alpar@9: {     int node;
alpar@9:       /* Node ID */
alpar@9:       int supply;
alpar@9:       /* Supply of that node */
alpar@9: };
alpar@9: 
alpar@9: struct csa
alpar@9: {     /* common storage area */
alpar@9:       glp_graph *G;
alpar@9:       int v_rhs, a_cap, a_cost;
alpar@9:       int seed;
alpar@9:       /* random number seed */
alpar@9:       int seed_original;
alpar@9:       /* the original seed from input */
alpar@9:       int two_way;
alpar@9:       /* 0: generate arcs in both direction for the basic grid, except
alpar@9:          for the arcs to/from the super node.  1: o/w */
alpar@9:       int n_node;
alpar@9:       /* total number of nodes in the network, numbered 1 to n_node,
alpar@9:          including the super node, which is the last one */
alpar@9:       int n_arc;
alpar@9:       /* total number of arcs in the network, counting EVERY arc. */
alpar@9:       int n_grid_arc;
alpar@9:       /* number of arcs in the basic grid, including the arcs to/from
alpar@9:          the super node */
alpar@9:       int n_source, n_sink;
alpar@9:       /* number of source and sink nodes */
alpar@9:       int avg_degree;
alpar@9:       /* average degree, arcs to and from the super node are counted */
alpar@9:       int t_supply;
alpar@9:       /* total supply in the network */
alpar@9:       int n1, n2;
alpar@9:       /* the two edges of the network grid.  n1 >= n2 */
alpar@9:       struct imbalance *source_list, *sink_list;
alpar@9:       /* head of the array of source/sink nodes */
alpar@9:       struct stat_para arc_costs;
alpar@9:       /* the distribution of arc costs */
alpar@9:       struct stat_para capacities;
alpar@9:       /* distribution of the capacities of the arcs */
alpar@9:       struct arcs *arc_list;
alpar@9:       /* head of the arc list array.  Arcs in this array are in the
alpar@9:          order of grid_arcs, arcs to/from super node, and other arcs */
alpar@9: };
alpar@9: 
alpar@9: #define G (csa->G)
alpar@9: #define v_rhs (csa->v_rhs)
alpar@9: #define a_cap (csa->a_cap)
alpar@9: #define a_cost (csa->a_cost)
alpar@9: #define seed (csa->seed)
alpar@9: #define seed_original (csa->seed_original)
alpar@9: #define two_way (csa->two_way)
alpar@9: #define n_node (csa->n_node)
alpar@9: #define n_arc (csa->n_arc)
alpar@9: #define n_grid_arc (csa->n_grid_arc)
alpar@9: #define n_source (csa->n_source)
alpar@9: #define n_sink (csa->n_sink)
alpar@9: #define avg_degree (csa->avg_degree)
alpar@9: #define t_supply (csa->t_supply)
alpar@9: #define n1 (csa->n1)
alpar@9: #define n2 (csa->n2)
alpar@9: #define source_list (csa->source_list)
alpar@9: #define sink_list (csa->sink_list)
alpar@9: #define arc_costs (csa->arc_costs)
alpar@9: #define capacities (csa->capacities)
alpar@9: #define arc_list (csa->arc_list)
alpar@9: 
alpar@9: static void assign_capacities(struct csa *csa);
alpar@9: static void assign_costs(struct csa *csa);
alpar@9: static void assign_imbalance(struct csa *csa);
alpar@9: static int exponential(struct csa *csa, double lambda[1]);
alpar@9: static struct arcs *gen_additional_arcs(struct csa *csa, struct arcs
alpar@9:       *arc_ptr);
alpar@9: static struct arcs *gen_basic_grid(struct csa *csa, struct arcs
alpar@9:       *arc_ptr);
alpar@9: static void gen_more_arcs(struct csa *csa, struct arcs *arc_ptr);
alpar@9: static void generate(struct csa *csa);
alpar@9: static void output(struct csa *csa);
alpar@9: static double randy(struct csa *csa);
alpar@9: static void select_source_sinks(struct csa *csa);
alpar@9: static int uniform(struct csa *csa, double a[2]);
alpar@9: 
alpar@9: int glp_gridgen(glp_graph *G_, int _v_rhs, int _a_cap, int _a_cost,
alpar@9:       const int parm[1+14])
alpar@9: {     struct csa _csa, *csa = &_csa;
alpar@9:       int n, ret;
alpar@9:       G = G_;
alpar@9:       v_rhs = _v_rhs;
alpar@9:       a_cap = _a_cap;
alpar@9:       a_cost = _a_cost;
alpar@9:       if (G != NULL)
alpar@9:       {  if (v_rhs >= 0 && v_rhs > G->v_size - (int)sizeof(double))
alpar@9:             xerror("glp_gridgen: v_rhs = %d; invalid offset\n", v_rhs);
alpar@9:          if (a_cap >= 0 && a_cap > G->a_size - (int)sizeof(double))
alpar@9:             xerror("glp_gridgen: a_cap = %d; invalid offset\n", a_cap);
alpar@9:          if (a_cost >= 0 && a_cost > G->a_size - (int)sizeof(double))
alpar@9:             xerror("glp_gridgen: a_cost = %d; invalid offset\n", a_cost)
alpar@9:                ;
alpar@9:       }
alpar@9:       /* Check the parameters for consistency. */
alpar@9:       if (!(parm[1] == 0 || parm[1] == 1))
alpar@9:       {  ret = 1;
alpar@9:          goto done;
alpar@9:       }
alpar@9:       if (parm[2] < 1)
alpar@9:       {  ret = 2;
alpar@9:          goto done;
alpar@9:       }
alpar@9:       if (!(10 <= parm[3] && parm[3] <= 40000))
alpar@9:       {  ret = 3;
alpar@9:          goto done;
alpar@9:       }
alpar@9:       if (!(1 <= parm[4] && parm[4] <= 40000))
alpar@9:       {  ret = 4;
alpar@9:          goto done;
alpar@9:       }
alpar@9:       if (!(parm[5] >= 0 && parm[6] >= 0 && parm[5] + parm[6] <=
alpar@9:          parm[3]))
alpar@9:       {  ret = 5;
alpar@9:          goto done;
alpar@9:       }
alpar@9:       if (!(1 <= parm[7] && parm[7] <= parm[3]))
alpar@9:       {  ret = 6;
alpar@9:          goto done;
alpar@9:       }
alpar@9:       if (parm[8] < 0)
alpar@9:       {  ret = 7;
alpar@9:          goto done;
alpar@9:       }
alpar@9:       if (!(parm[9] == 1 || parm[9] == 2))
alpar@9:       {  ret = 8;
alpar@9:          goto done;
alpar@9:       }
alpar@9:       if (parm[9] == 1 && parm[10] > parm[11] ||
alpar@9:           parm[9] == 2 && parm[10] < 1)
alpar@9:       {  ret = 9;
alpar@9:          goto done;
alpar@9:       }
alpar@9:       if (!(parm[12] == 1 || parm[12] == 2))
alpar@9:       {  ret = 10;
alpar@9:          goto done;
alpar@9:       }
alpar@9:       if (parm[12] == 1 && !(0 <= parm[13] && parm[13] <= parm[14]) ||
alpar@9:           parm[12] == 2 && parm[13] < 1)
alpar@9:       {  ret = 11;
alpar@9:          goto done;
alpar@9:       }
alpar@9:       /* Initialize the graph object. */
alpar@9:       if (G != NULL)
alpar@9:       {  glp_erase_graph(G, G->v_size, G->a_size);
alpar@9:          glp_set_graph_name(G, "GRIDGEN");
alpar@9:       }
alpar@9:       /* Copy the generator parameters. */
alpar@9:       two_way = parm[1];
alpar@9:       seed_original = seed = parm[2];
alpar@9:       n_node = parm[3];
alpar@9:       n = parm[4];
alpar@9:       n_source = parm[5];
alpar@9:       n_sink = parm[6];
alpar@9:       avg_degree = parm[7];
alpar@9:       t_supply = parm[8];
alpar@9:       arc_costs.distribution = parm[9];
alpar@9:       if (parm[9] == 1)
alpar@9:       {  arc_costs.parameter[0] = parm[10];
alpar@9:          arc_costs.parameter[1] = parm[11];
alpar@9:       }
alpar@9:       else
alpar@9:       {  arc_costs.parameter[0] = (double)parm[10] / 100.0;
alpar@9:          arc_costs.parameter[1] = 0.0;
alpar@9:       }
alpar@9:       capacities.distribution = parm[12];
alpar@9:       if (parm[12] == 1)
alpar@9:       {  capacities.parameter[0] = parm[13];
alpar@9:          capacities.parameter[1] = parm[14];
alpar@9:       }
alpar@9:       else
alpar@9:       {  capacities.parameter[0] = (double)parm[13] / 100.0;
alpar@9:          capacities.parameter[1] = 0.0;
alpar@9:       }
alpar@9:       /* Calculate the edge lengths of the grid according to the
alpar@9:          input. */
alpar@9:       if (n * n >= n_node)
alpar@9:       {  n1 = n;
alpar@9:          n2 = (int)((double)n_node / (double)n + 0.5);
alpar@9:       }
alpar@9:       else
alpar@9:       {  n2 = n;
alpar@9:          n1 = (int)((double)n_node / (double)n + 0.5);
alpar@9:       }
alpar@9:       /* Recalculate the total number of nodes and plus 1 for the super
alpar@9:          node. */
alpar@9:       n_node = n1 * n2 + 1;
alpar@9:       n_arc = n_node * avg_degree;
alpar@9:       n_grid_arc = (two_way + 1) * ((n1 - 1) * n2 + (n2 - 1) * n1) +
alpar@9:          n_source + n_sink;
alpar@9:       if (n_grid_arc > n_arc) n_arc = n_grid_arc;
alpar@9:       arc_list = xcalloc(n_arc, sizeof(struct arcs));
alpar@9:       source_list = xcalloc(n_source, sizeof(struct imbalance));
alpar@9:       sink_list = xcalloc(n_sink, sizeof(struct imbalance));
alpar@9:       /* Generate a random network. */
alpar@9:       generate(csa);
alpar@9:       /* Output the network. */
alpar@9:       output(csa);
alpar@9:       /* Free all allocated memory. */
alpar@9:       xfree(arc_list);
alpar@9:       xfree(source_list);
alpar@9:       xfree(sink_list);
alpar@9:       /* The instance has been successfully generated. */
alpar@9:       ret = 0;
alpar@9: done: return ret;
alpar@9: }
alpar@9: 
alpar@9: #undef random
alpar@9: 
alpar@9: static void assign_capacities(struct csa *csa)
alpar@9: {     /* Assign a capacity to each arc. */
alpar@9:       struct arcs *arc_ptr = arc_list;
alpar@9:       int (*random)(struct csa *csa, double *);
alpar@9:       int i;
alpar@9:       /* Determine the random number generator to use. */
alpar@9:       switch (arc_costs.distribution)
alpar@9:       {  case UNIFORM:
alpar@9:             random = uniform;
alpar@9:             break;
alpar@9:          case EXPONENTIAL:
alpar@9:             random = exponential;
alpar@9:             break;
alpar@9:          default:
alpar@9:             xassert(csa != csa);
alpar@9:       }
alpar@9:       /* Assign capacities to grid arcs. */
alpar@9:       for (i = n_source + n_sink; i < n_grid_arc; i++, arc_ptr++)
alpar@9:          arc_ptr->u = random(csa, capacities.parameter);
alpar@9:       i = i - n_source - n_sink;
alpar@9:       /* Assign capacities to arcs to/from supernode. */
alpar@9:       for (; i < n_grid_arc; i++, arc_ptr++)
alpar@9:          arc_ptr->u = t_supply;
alpar@9:       /* Assign capacities to all other arcs. */
alpar@9:       for (; i < n_arc; i++, arc_ptr++)
alpar@9:          arc_ptr->u = random(csa, capacities.parameter);
alpar@9:       return;
alpar@9: }
alpar@9: 
alpar@9: static void assign_costs(struct csa *csa)
alpar@9: {     /* Assign a cost to each arc. */
alpar@9:       struct arcs *arc_ptr = arc_list;
alpar@9:       int (*random)(struct csa *csa, double *);
alpar@9:       int i;
alpar@9:       /* A high cost assigned to arcs to/from the supernode. */
alpar@9:       int high_cost;
alpar@9:       /* The maximum cost assigned to arcs in the base grid. */
alpar@9:       int max_cost = 0;
alpar@9:       /* Determine the random number generator to use. */
alpar@9:       switch (arc_costs.distribution)
alpar@9:       {  case UNIFORM:
alpar@9:             random = uniform;
alpar@9:             break;
alpar@9:          case EXPONENTIAL:
alpar@9:             random = exponential;
alpar@9:             break;
alpar@9:          default:
alpar@9:             xassert(csa != csa);
alpar@9:       }
alpar@9:       /* Assign costs to arcs in the base grid. */
alpar@9:       for (i = n_source + n_sink; i < n_grid_arc; i++, arc_ptr++)
alpar@9:       {  arc_ptr->cost = random(csa, arc_costs.parameter);
alpar@9:          if (max_cost < arc_ptr->cost) max_cost = arc_ptr->cost;
alpar@9:       }
alpar@9:       i = i - n_source - n_sink;
alpar@9:       /* Assign costs to arcs to/from the super node. */
alpar@9:       high_cost = max_cost * 2;
alpar@9:       for (; i < n_grid_arc; i++, arc_ptr++)
alpar@9:          arc_ptr->cost = high_cost;
alpar@9:       /* Assign costs to all other arcs. */
alpar@9:       for (; i < n_arc; i++, arc_ptr++)
alpar@9:          arc_ptr->cost = random(csa, arc_costs.parameter);
alpar@9:       return;
alpar@9: }
alpar@9: 
alpar@9: static void assign_imbalance(struct csa *csa)
alpar@9: {     /* Assign an imbalance to each node. */
alpar@9:       int total, i;
alpar@9:       double avg;
alpar@9:       struct imbalance *ptr;
alpar@9:       /* assign the supply nodes */
alpar@9:       avg = 2.0 * t_supply / n_source;
alpar@9:       do
alpar@9:       {  for (i = 1, total = t_supply, ptr = source_list + 1;
alpar@9:             i < n_source; i++, ptr++)
alpar@9:          {  ptr->supply = (int)(randy(csa) * avg + 0.5);
alpar@9:             total -= ptr->supply;
alpar@9:          }
alpar@9:          source_list->supply = total;
alpar@9:       }
alpar@9:       /* redo all if the assignment "overshooted" */
alpar@9:       while (total <= 0);
alpar@9:       /* assign the demand nodes */
alpar@9:       avg = -2.0 * t_supply / n_sink;
alpar@9:       do
alpar@9:       {  for (i = 1, total = t_supply, ptr = sink_list + 1;
alpar@9:             i < n_sink; i++, ptr++)
alpar@9:          {  ptr->supply = (int)(randy(csa) * avg - 0.5);
alpar@9:             total += ptr->supply;
alpar@9:          }
alpar@9:          sink_list->supply = - total;
alpar@9:       }
alpar@9:       while (total <= 0);
alpar@9:       return;
alpar@9: }
alpar@9: 
alpar@9: static int exponential(struct csa *csa, double lambda[1])
alpar@9: {     /* Returns an "exponentially distributed" integer with parameter
alpar@9:          lambda. */
alpar@9:       return ((int)(- lambda[0] * log((double)randy(csa)) + 0.5));
alpar@9: }
alpar@9: 
alpar@9: static struct arcs *gen_additional_arcs(struct csa *csa, struct arcs
alpar@9:       *arc_ptr)
alpar@9: {     /* Generate an arc from each source to the supernode and from
alpar@9:          supernode to each sink. */
alpar@9:       int i;
alpar@9:       for (i = 0; i < n_source; i++, arc_ptr++)
alpar@9:       {  arc_ptr->from = source_list[i].node;
alpar@9:          arc_ptr->to = n_node;
alpar@9:       }
alpar@9:       for (i = 0; i < n_sink; i++, arc_ptr++)
alpar@9:       {  arc_ptr->to = sink_list[i].node;
alpar@9:          arc_ptr->from = n_node;
alpar@9:       }
alpar@9:       return arc_ptr;
alpar@9: }
alpar@9: 
alpar@9: static struct arcs *gen_basic_grid(struct csa *csa, struct arcs
alpar@9:       *arc_ptr)
alpar@9: {     /* Generate the basic grid. */
alpar@9:       int direction = 1, i, j, k;
alpar@9:       if (two_way)
alpar@9:       {  /* Generate an arc in each direction. */
alpar@9:          for (i = 1; i < n_node; i += n1)
alpar@9:          {  for (j = i, k = j + n1 - 1; j < k; j++)
alpar@9:             {  arc_ptr->from = j;
alpar@9:                arc_ptr->to = j + 1;
alpar@9:                arc_ptr++;
alpar@9:                arc_ptr->from = j + 1;
alpar@9:                arc_ptr->to = j;
alpar@9:                arc_ptr++;
alpar@9:             }
alpar@9:          }
alpar@9:          for (i = 1; i <= n1; i++)
alpar@9:          {  for (j = i + n1; j < n_node; j += n1)
alpar@9:             {  arc_ptr->from = j;
alpar@9:                arc_ptr->to = j - n1;
alpar@9:                arc_ptr++;
alpar@9:                arc_ptr->from = j - n1;
alpar@9:                arc_ptr->to = j;
alpar@9:                arc_ptr++;
alpar@9:             }
alpar@9:          }
alpar@9:       }
alpar@9:       else
alpar@9:       {  /* Generate one arc in each direction. */
alpar@9:          for (i = 1; i < n_node; i += n1)
alpar@9:          {  if (direction == 1)
alpar@9:                j = i;
alpar@9:             else
alpar@9:                j = i + 1;
alpar@9:             for (k = j + n1 - 1; j < k; j++)
alpar@9:             {  arc_ptr->from = j;
alpar@9:                arc_ptr->to = j + direction;
alpar@9:                arc_ptr++;
alpar@9:             }
alpar@9:             direction = - direction;
alpar@9:          }
alpar@9:          for (i = 1; i <= n1; i++)
alpar@9:          {  j = i + n1;
alpar@9:             if (direction == 1)
alpar@9:             {  for (; j < n_node; j += n1)
alpar@9:                {  arc_ptr->from = j - n1;
alpar@9:                   arc_ptr->to = j;
alpar@9:                   arc_ptr++;
alpar@9:                }
alpar@9:             }
alpar@9:             else
alpar@9:             {  for (; j < n_node; j += n1)
alpar@9:                {  arc_ptr->from = j - n1;
alpar@9:                   arc_ptr->to = j;
alpar@9:                   arc_ptr++;
alpar@9:                }
alpar@9:             }
alpar@9:             direction = - direction;
alpar@9:          }
alpar@9:       }
alpar@9:       return arc_ptr;
alpar@9: }
alpar@9: 
alpar@9: static void gen_more_arcs(struct csa *csa, struct arcs *arc_ptr)
alpar@9: {     /* Generate random arcs to meet the specified density. */
alpar@9:       int i;
alpar@9:       double ab[2];
alpar@9:       ab[0] = 0.9;
alpar@9:       ab[1] = n_node - 0.99;  /* upper limit is n_node-1 because the
alpar@9:                                  supernode cannot be selected */
alpar@9:       for (i = n_grid_arc; i < n_arc; i++, arc_ptr++)
alpar@9:       {  arc_ptr->from = uniform(csa, ab);
alpar@9:          arc_ptr->to = uniform(csa, ab);
alpar@9:          if (arc_ptr->from == arc_ptr->to)
alpar@9:          {  arc_ptr--;
alpar@9:             i--;
alpar@9:          }
alpar@9:       }
alpar@9:       return;
alpar@9: }
alpar@9: 
alpar@9: static void generate(struct csa *csa)
alpar@9: {     /* Generate a random network. */
alpar@9:       struct arcs *arc_ptr = arc_list;
alpar@9:       arc_ptr = gen_basic_grid(csa, arc_ptr);
alpar@9:       select_source_sinks(csa);
alpar@9:       arc_ptr = gen_additional_arcs(csa, arc_ptr);
alpar@9:       gen_more_arcs(csa, arc_ptr);
alpar@9:       assign_costs(csa);
alpar@9:       assign_capacities(csa);
alpar@9:       assign_imbalance(csa);
alpar@9:       return;
alpar@9: }
alpar@9: 
alpar@9: static void output(struct csa *csa)
alpar@9: {     /* Output the network in DIMACS format. */
alpar@9:       struct arcs *arc_ptr;
alpar@9:       struct imbalance *imb_ptr;
alpar@9:       int i;
alpar@9:       if (G != NULL) goto skip;
alpar@9:       /* Output "c", "p" records. */
alpar@9:       xprintf("c generated by GRIDGEN\n");
alpar@9:       xprintf("c seed %d\n", seed_original);
alpar@9:       xprintf("c nodes %d\n", n_node);
alpar@9:       xprintf("c grid size %d X %d\n", n1, n2);
alpar@9:       xprintf("c sources %d sinks %d\n", n_source, n_sink);
alpar@9:       xprintf("c avg. degree %d\n", avg_degree);
alpar@9:       xprintf("c supply %d\n", t_supply);
alpar@9:       switch (arc_costs.distribution)
alpar@9:       {  case UNIFORM:
alpar@9:             xprintf("c arc costs: UNIFORM distr. min %d max %d\n",
alpar@9:                (int)arc_costs.parameter[0],
alpar@9:                (int)arc_costs.parameter[1]);
alpar@9:             break;
alpar@9:          case EXPONENTIAL:
alpar@9:             xprintf("c arc costs: EXPONENTIAL distr. lambda %d\n",
alpar@9:                (int)arc_costs.parameter[0]);
alpar@9:             break;
alpar@9:          default:
alpar@9:             xassert(csa != csa);
alpar@9:       }
alpar@9:       switch (capacities.distribution)
alpar@9:       {  case UNIFORM:
alpar@9:             xprintf("c arc caps :  UNIFORM distr. min %d max %d\n",
alpar@9:                (int)capacities.parameter[0],
alpar@9:                (int)capacities.parameter[1]);
alpar@9:             break;
alpar@9:          case EXPONENTIAL:
alpar@9:             xprintf("c arc caps :  EXPONENTIAL distr. %d lambda %d\n",
alpar@9:                (int)capacities.parameter[0]);
alpar@9:             break;
alpar@9:          default:
alpar@9:             xassert(csa != csa);
alpar@9:       }
alpar@9: skip: if (G == NULL)
alpar@9:          xprintf("p min %d %d\n", n_node, n_arc);
alpar@9:       else
alpar@9:       {  glp_add_vertices(G, n_node);
alpar@9:          if (v_rhs >= 0)
alpar@9:          {  double zero = 0.0;
alpar@9:             for (i = 1; i <= n_node; i++)
alpar@9:             {  glp_vertex *v = G->v[i];
alpar@9:                memcpy((char *)v->data + v_rhs, &zero, sizeof(double));
alpar@9:             }
alpar@9:          }
alpar@9:       }
alpar@9:       /* Output "n node supply". */
alpar@9:       for (i = 0, imb_ptr = source_list; i < n_source; i++, imb_ptr++)
alpar@9:       {  if (G == NULL)
alpar@9:             xprintf("n %d %d\n", imb_ptr->node, imb_ptr->supply);
alpar@9:          else
alpar@9:          {  if (v_rhs >= 0)
alpar@9:             {  double temp = (double)imb_ptr->supply;
alpar@9:                glp_vertex *v = G->v[imb_ptr->node];
alpar@9:                memcpy((char *)v->data + v_rhs, &temp, sizeof(double));
alpar@9:             }
alpar@9:          }
alpar@9:       }
alpar@9:       for (i = 0, imb_ptr = sink_list; i < n_sink; i++, imb_ptr++)
alpar@9:       {  if (G == NULL)
alpar@9:             xprintf("n %d %d\n", imb_ptr->node, imb_ptr->supply);
alpar@9:          else
alpar@9:          {  if (v_rhs >= 0)
alpar@9:             {  double temp = (double)imb_ptr->supply;
alpar@9:                glp_vertex *v = G->v[imb_ptr->node];
alpar@9:                memcpy((char *)v->data + v_rhs, &temp, sizeof(double));
alpar@9:             }
alpar@9:          }
alpar@9:       }
alpar@9:       /* Output "a from to lowcap=0 hicap cost". */
alpar@9:       for (i = 0, arc_ptr = arc_list; i < n_arc; i++, arc_ptr++)
alpar@9:       {  if (G == NULL)
alpar@9:             xprintf("a %d %d 0 %d %d\n", arc_ptr->from, arc_ptr->to,
alpar@9:                arc_ptr->u, arc_ptr->cost);
alpar@9:          else
alpar@9:          {  glp_arc *a = glp_add_arc(G, arc_ptr->from, arc_ptr->to);
alpar@9:             if (a_cap >= 0)
alpar@9:             {  double temp = (double)arc_ptr->u;
alpar@9:                memcpy((char *)a->data + a_cap, &temp, sizeof(double));
alpar@9:             }
alpar@9:             if (a_cost >= 0)
alpar@9:             {  double temp = (double)arc_ptr->cost;
alpar@9:                memcpy((char *)a->data + a_cost, &temp, sizeof(double));
alpar@9:             }
alpar@9:          }
alpar@9:       }
alpar@9:       return;
alpar@9: }
alpar@9: 
alpar@9: static double randy(struct csa *csa)
alpar@9: {     /* Returns a random number between 0.0 and 1.0.
alpar@9:          See Ward Cheney & David Kincaid, "Numerical Mathematics and
alpar@9:          Computing," 2Ed, pp. 335. */
alpar@9:       seed = 16807 * seed % 2147483647;
alpar@9:       if (seed < 0) seed = - seed;
alpar@9:       return seed * 4.6566128752459e-10;
alpar@9: }
alpar@9: 
alpar@9: static void select_source_sinks(struct csa *csa)
alpar@9: {     /* Randomly select the source nodes and sink nodes. */
alpar@9:       int i, *int_ptr;
alpar@9:       int *temp_list;   /* a temporary list of nodes */
alpar@9:       struct imbalance *ptr;
alpar@9:       double ab[2];     /* parameter for random number generator */
alpar@9:       ab[0] = 0.9;
alpar@9:       ab[1] = n_node - 0.99;  /* upper limit is n_node-1 because the
alpar@9:                                  supernode cannot be selected */
alpar@9:       temp_list = xcalloc(n_node, sizeof(int));
alpar@9:       for (i = 0, int_ptr = temp_list; i < n_node; i++, int_ptr++)
alpar@9:          *int_ptr = 0;
alpar@9:       /* Select the source nodes. */
alpar@9:       for (i = 0, ptr = source_list; i < n_source; i++, ptr++)
alpar@9:       {  ptr->node = uniform(csa, ab);
alpar@9:          if (temp_list[ptr->node] == 1) /* check for duplicates */
alpar@9:          {  ptr--;
alpar@9:             i--;
alpar@9:          }
alpar@9:          else
alpar@9:             temp_list[ptr->node] = 1;
alpar@9:       }
alpar@9:       /* Select the sink nodes. */
alpar@9:       for (i = 0, ptr = sink_list; i < n_sink; i++, ptr++)
alpar@9:       {  ptr->node = uniform(csa, ab);
alpar@9:          if (temp_list[ptr->node] == 1)
alpar@9:          {  ptr--;
alpar@9:             i--;
alpar@9:          }
alpar@9:          else
alpar@9:             temp_list[ptr->node] = 1;
alpar@9:       }
alpar@9:       xfree(temp_list);
alpar@9:       return;
alpar@9: }
alpar@9: 
alpar@9: int uniform(struct csa *csa, double a[2])
alpar@9: {     /* Generates an integer uniformly selected from [a[0],a[1]]. */
alpar@9:       return (int)((a[1] - a[0]) * randy(csa) + a[0] + 0.5);
alpar@9: }
alpar@9: 
alpar@9: /**********************************************************************/
alpar@9: 
alpar@9: #if 0
alpar@9: int main(void)
alpar@9: {     int parm[1+14];
alpar@9:       double temp;
alpar@9:       scanf("%d", &parm[1]);
alpar@9:       scanf("%d", &parm[2]);
alpar@9:       scanf("%d", &parm[3]);
alpar@9:       scanf("%d", &parm[4]);
alpar@9:       scanf("%d", &parm[5]);
alpar@9:       scanf("%d", &parm[6]);
alpar@9:       scanf("%d", &parm[7]);
alpar@9:       scanf("%d", &parm[8]);
alpar@9:       scanf("%d", &parm[9]);
alpar@9:       if (parm[9] == 1)
alpar@9:       {  scanf("%d", &parm[10]);
alpar@9:          scanf("%d", &parm[11]);
alpar@9:       }
alpar@9:       else
alpar@9:       {  scanf("%le", &temp);
alpar@9:          parm[10] = (int)(100.0 * temp + .5);
alpar@9:          parm[11] = 0;
alpar@9:       }
alpar@9:       scanf("%d", &parm[12]);
alpar@9:       if (parm[12] == 1)
alpar@9:       {  scanf("%d", &parm[13]);
alpar@9:          scanf("%d", &parm[14]);
alpar@9:       }
alpar@9:       else
alpar@9:       {  scanf("%le", &temp);
alpar@9:          parm[13] = (int)(100.0 * temp + .5);
alpar@9:          parm[14] = 0;
alpar@9:       }
alpar@9:       glp_gridgen(NULL, 0, 0, 0, parm);
alpar@9:       return 0;
alpar@9: }
alpar@9: #endif
alpar@9: 
alpar@9: /* eof */