Try our new documentation site (beta).


/* Copyright 2016, Gurobi Optimization, Inc. */

/* Solve a model with different values of the Method parameter;
   show which value gives the shortest solve time. */

#include <stdlib.h>
#include <stdio.h>
#include "gurobi_c.h"

main(int   argc,
     char *argv[])
  GRBenv   *env = NULL, *menv;
  GRBmodel *m = NULL;
  int       error = 0;
  int       i;
  int       optimstatus;
  int       bestMethod = -1;
  double    bestTime;

  if (argc < 2)
    fprintf(stderr, "Usage: lpmethod_c filename\n");

  error = GRBloadenv(&env, "lpmethod.log");
  if (error) goto QUIT;

  /* Read model */
  error = GRBreadmodel(env, argv[1], &m);
  if (error) goto QUIT;
  menv = GRBgetenv(m);
  error = GRBgetdblparam(menv, "TimeLimit", &bestTime);
  if (error) goto QUIT;

  /* Solve the model with different values of Method */
  for (i = 0; i <= 2; ++i)
    error = GRBresetmodel(m);
    if (error) goto QUIT;
    error = GRBsetintparam(menv, "Method", i);
    if (error) goto QUIT;
    error = GRBoptimize(m);
    if (error) goto QUIT;
    error = GRBgetintattr(m, "Status", &optimstatus);
    if (error) goto QUIT;
    if (optimstatus == GRB_OPTIMAL) {
      error = GRBgetdblattr(m, "Runtime", &bestTime);
      if (error) goto QUIT;
      bestMethod = i;
      /* Reduce the TimeLimit parameter to save time
         with other methods */
      error = GRBsetdblparam(menv, "TimeLimit", bestTime);
      if (error) goto QUIT;

  /* Report which method was fastest */
  if (bestMethod == -1) {
    printf("Unable to solve this model\n");
  } else {
    printf("Solved in %f seconds with Method: %i\n",
           bestTime, bestMethod);


  /* Error reporting */

  if (error)
    printf("ERROR: %s\n", GRBgeterrormsg(env));

  /* Free model */


  /* Free environment */


  return 0;

Try Gurobi for Free

Choose the evaluation license that fits you best, and start working with our Expert Team for technical guidance and support.

Evaluation License
Get a free, full-featured license of the Gurobi Optimizer to experience the performance, support, benchmarking and tuning services we provide as part of our product offering.
Academic License
Gurobi supports the teaching and use of optimization within academic institutions. We offer free, full-featured copies of Gurobi for use in class, and for research.
Cloud Trial

Request free trial hours, so you can see how quickly and easily a model can be solved on the cloud.