params_c.c
/ * 2023年版权,Gurobi优狗万app足彩化,LLC * / / *使用参数模型。几秒钟的MIP解决不同的参数。选择最小的MIP的差距,优化是恢复,直到找到最优解。* / # include < stdlib。h > # include < stdio。h > # include <数学。h > # include " gurobi_c。h“int主要(int命令行参数个数,char * argv []) {GRBenv * env = NULL, * modelenv = NULL, * bestenv =零;GRBmodel *模型= NULL, * bestmodel =零;int错误= 0;我,int ismip mipfocus;双bestgap差距; if (argc < 2) { fprintf(stderr, "Usage: params_c filename\n"); exit(1); } error = GRBloadenv(&env, "params.log"); if (error) goto QUIT; /* Read model and verify that it is a MIP */ error = GRBreadmodel(env, argv[1], &model); if (error) goto QUIT; error = GRBgetintattr(model, "IsMIP", &ismip); if (error) goto QUIT; if (ismip == 0) { printf("The model is not an integer program\n"); exit(1); } /* Set a 2 second time limit */ modelenv = GRBgetenv(model); if (!modelenv) { printf("Cannot retrieve model environment\n"); exit(1); } error = GRBsetdblparam(modelenv, "TimeLimit", 2); if (error) goto QUIT; /* Now solve the model with different values of MIPFocus */ bestmodel = GRBcopymodel(model); if (!bestmodel) { printf("Cannot copy model\n"); exit(1); } error = GRBoptimize(bestmodel); if (error) goto QUIT; error = GRBgetdblattr(bestmodel, "MIPGap", &bestgap); if (error) goto QUIT; for (i = 1; i <= 3; ++i) { error = GRBreset(model, 0); if (error) goto QUIT; modelenv = GRBgetenv(model); if (!modelenv) { printf("Cannot retrieve model environment\n"); exit(1); } error = GRBsetintparam(modelenv, "MIPFocus", i); if (error) goto QUIT; error = GRBoptimize(model); if (error) goto QUIT; error = GRBgetdblattr(model, "MIPGap", &gap); if (error) goto QUIT; if (bestgap > gap) { GRBmodel *tmp = bestmodel; bestmodel = model; model = tmp; bestgap = gap; } } /* Finally, free the extra model, reset the time limit and continue to solve the best model to optimality */ GRBfreemodel(model); bestenv = GRBgetenv(bestmodel); if (!bestenv) { printf("Cannot retrieve best model environment\n"); exit(1); } error = GRBsetdblparam(bestenv, "TimeLimit", GRB_INFINITY); if (error) goto QUIT; error = GRBoptimize(bestmodel); if (error) goto QUIT; error = GRBgetintparam(bestenv, "MIPFocus", &mipfocus); if (error) goto QUIT; printf("Solved with MIPFocus: %i\n", mipfocus); QUIT: /* Error reporting */ if (error) { printf("ERROR: %s\n", GRBgeterrormsg(env)); exit(1); } /* Free best model */ GRBfreemodel(bestmodel); /* Free environment */ GRBfreeenv(env); return 0; }
