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lpmethod_c.c
/* Copyright 2024, Gurobi Optimization, LLC */ /* 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" int 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"); exit(1); } 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 = GRBreset(m, 0); 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); } QUIT: /* Error reporting */ if (error) { printf("ERROR: %s\n", GRBgeterrormsg(env)); exit(1); } /* Free model */ GRBfreemodel(m); /* Free environment */ GRBfreeenv(env); return 0; }