Esempio n. 1
0
File: windll.c Progetto: ks6g10/CA
/* Set the name of a variable column */
long __declspec(dllexport) WINAPI _set_col_name(lprec *lp, long column, char *new_name)
 {
  long ret;

  if (lp != NULL) {
   freebuferror();
   ret = set_col_name(lp, column, new_name);
  }
  else
   ret = 0;
  return(ret);
 }
// TODO there's a seriouxx need for refactoring here !
Solution LpsolveAdaptator::getAdmissibleSolution(LinearProblem * lp) {
	lprec *lprec;
	int nbCol = lp->getVariables().size();
	lprec = make_lp(0, nbCol);

	if (lprec == NULL) {
		// TODO raise an exception
	}

	/* set variables name to ease debugging */
	for (int i = 0; i < (int)lp->getVariables().size(); ++i) {
		Variable * var = (lp->getVariables())[i];
		set_col_name(lprec, i+1, var->getNameToChar());
		if (var->isBinary()) {
			set_binary(lprec, i+1, TRUE);
		}
	}

	/* to build the model faster when adding constraints one at a time */
	set_add_rowmode(lprec, TRUE);

	for (int i = 0; i < (int)(lp->getConstraints().size()); ++i) {
		// FIXME there's a bug here but I can't find it
		Constraint c = (Constraint)(lp->getConstraints()[i]);
		TermList terms = c.getTerms();
		int col[terms.size()];
		REAL row[terms.size()];
		int j = 0;
		for (TermList::const_iterator it = terms.begin(); it != terms.end();
				++it, ++j) {
			// TODO check if this is fixed
			col[j] = ((Term)*it).getVariable().getPosition();
			row[j] = ((Term)*it).getCoeff();
		}
		// WARNING the Consraint uses the same operator values than in lp_lib.h
		if (!add_constraintex(lprec, j, row, col, c.getOperator(), c.getBound())) {
			// TODO raise an exception
		}
	}

	/* the objective function requires rowmode to be off */
	set_add_rowmode(lprec, FALSE);

	return getSolution(lprec);
}
Esempio n. 3
0
int demoImplicit(void)
{
# if defined ERROR
#  undef ERROR
# endif
# define ERROR() { fprintf(stderr, "Error\n"); return(1); }
  lprec *lp;
  int majorversion, minorversion, release, build;
  char buf[1024];

  if ((lp = make_lp(0,4)) == NULL)
    ERROR();

  lp_solve_version(&majorversion, &minorversion, &release, &build);

  /* let's first demonstrate the logfunc callback feature */
  put_logfunc(lp, Mylogfunc, 0);
  sprintf(buf, "lp_solve %d.%d.%d.%d demo\n\n", majorversion, minorversion, release, build);
  print_str(lp, buf);
  solve(lp); /* just to see that a message is send via the logfunc routine ... */
  /* ok, that is enough, no more callback */
  put_logfunc(lp, NULL, 0);

  /* Now redirect all output to a file */
  /* set_outputfile(lp, "result.txt"); */

  /* set an abort function. Again optional */
  put_abortfunc(lp, Myctrlcfunc, 0);

  /* set a message function. Again optional */
  put_msgfunc(lp, Mymsgfunc, 0, MSG_PRESOLVE | MSG_LPFEASIBLE | MSG_LPOPTIMAL | MSG_MILPEQUAL | MSG_MILPFEASIBLE | MSG_MILPBETTER);

  printf("lp_solve %d.%d.%d.%d demo\n\n", majorversion, minorversion, release, build);
  printf("This demo will show most of the features of lp_solve %d.%d.%d.%d\n", majorversion, minorversion, release, build);
  press_ret();
  printf("\nWe start by creating a new problem with 4 variables and 0 constraints\n");
  printf("We use: lp=make_lp(0,4);\n");
  press_ret();

  printf("We can show the current problem with print_lp(lp)\n");
  print_lp(lp);
  press_ret();
  printf("Now we add some constraints\n");
  printf("str_add_constraint(lp, \"3 2 2 1\" ,LE,4)\n");
  printf("This is the string version of add_constraint. For the normal version\n");
  printf("of add_constraint see the help file.\n");
  if (!str_add_constraint(lp, "3 2 2 1", LE, 4))
    ERROR();
  print_lp(lp);
  press_ret();
  printf("str_add_constraint(lp, \"0 4 3 1\" ,GE,3)\n");
  if (!str_add_constraint(lp, "0 4 3 1", GE, 3))
    ERROR();
  print_lp(lp);
  press_ret();
  printf("Set the objective function\n");
  printf("str_set_obj_fn(lp, \"2 3 -2 3\")\n");
  if (!str_set_obj_fn(lp, "2 3 -2 3"))
    ERROR();
  print_lp(lp);
  press_ret();
  printf("Now solve the problem with printf(solve(lp));\n");
  printf("%d",solve(lp));
  press_ret();
  printf("The value is 0, this means we found an optimal solution\n");
  printf("We can display this solution with print_objective(lp) and print_solution(lp)\n");
  print_objective(lp);
  print_solution(lp, 1);
  print_constraints(lp, 1);

  press_ret();
  printf("The dual variables of the solution are printed with\n");
  printf("print_duals(lp);\n");
  print_duals(lp);
  press_ret();
  printf("We can change a single element in the matrix with\n");
  printf("set_mat(lp,2,1,0.5)\n");
  if (!set_mat(lp,2,1,0.5))
    ERROR();
  print_lp(lp);
  press_ret();
  printf("If we want to maximize the objective function use set_maxim(lp);\n");
  set_maxim(lp);
  print_lp(lp);
  press_ret();
  printf("after solving this gives us:\n");
  solve(lp);
  print_objective(lp);
  print_solution(lp, 1);
  print_constraints(lp, 1);
  print_duals(lp);
  press_ret();
  printf("Change the value of a rhs element with set_rh(lp,1,7.45)\n");
  set_rh(lp,1,7.45);
  print_lp(lp);
  solve(lp);
  print_objective(lp);
  print_solution(lp, 1);
  print_constraints(lp, 1);
  press_ret();
  printf("We change %s to the integer type with\n", get_col_name(lp, 4));
  printf("set_int(lp, 4, TRUE)\n");
  set_int(lp, 4, TRUE);
  print_lp(lp);
  printf("We set branch & bound debugging on with set_debug(lp, TRUE)\n");
  set_debug(lp, TRUE);
  printf("and solve...\n");
  press_ret();
  solve(lp);
  print_objective(lp);
  print_solution(lp, 1);
  print_constraints(lp, 1);
  press_ret();
  printf("We can set bounds on the variables with\n");
  printf("set_lowbo(lp,2,2); & set_upbo(lp,4,5.3)\n");
  set_lowbo(lp,2,2);
  set_upbo(lp,4,5.3);
  print_lp(lp);
  press_ret();
  solve(lp);
  print_objective(lp);
  print_solution(lp, 1);
  print_constraints(lp, 1);
  press_ret();
  printf("Now remove a constraint with del_constraint(lp, 1)\n");
  del_constraint(lp,1);
  print_lp(lp);
  printf("Add an equality constraint\n");
  if (!str_add_constraint(lp, "1 2 1 4", EQ, 8))
    ERROR();
  print_lp(lp);
  press_ret();
  printf("A column can be added with:\n");
  printf("str_add_column(lp,\"3 2 2\");\n");
  if (!str_add_column(lp,"3 2 2"))
    ERROR();
  print_lp(lp);
  press_ret();
  printf("A column can be removed with:\n");
  printf("del_column(lp,3);\n");
  del_column(lp,3);
  print_lp(lp);
  press_ret();
  printf("We can use automatic scaling with:\n");
  printf("set_scaling(lp, SCALE_MEAN);\n");
  set_scaling(lp, SCALE_MEAN);
  print_lp(lp);
  press_ret();
  printf("The function get_mat(lprec *lp, int row, int column) returns a single\n");
  printf("matrix element\n");
  printf("%s get_mat(lp,2,3), get_mat(lp,1,1); gives\n","printf(\"%f %f\\n\",");
  printf("%f %f\n", (double)get_mat(lp,2,3), (double)get_mat(lp,1,1));
  printf("Notice that get_mat returns the value of the original unscaled problem\n");
  press_ret();
  printf("If there are any integer type variables, then only the rows are scaled\n");
  printf("set_scaling(lp, SCALE_MEAN);\n");
  set_scaling(lp, SCALE_MEAN);
  printf("set_int(lp,3,FALSE);\n");
  set_int(lp,3,FALSE);
  print_lp(lp);
  press_ret();
  solve(lp);
  printf("print_objective, print_solution gives the solution to the original problem\n");
  print_objective(lp);
  print_solution(lp, 1);
  print_constraints(lp, 1);
  press_ret();
  printf("Scaling is turned off with unscale(lp);\n");
  unscale(lp);
  print_lp(lp);
  press_ret();
  printf("Now turn B&B debugging off and simplex tracing on with\n");
  printf("set_debug(lp, FALSE), set_trace(lp, TRUE) and solve(lp)\n");
  set_debug(lp, FALSE);
  set_trace(lp, TRUE);
  press_ret();
  solve(lp);
  printf("Where possible, lp_solve will start at the last found basis\n");
  printf("We can reset the problem to the initial basis with\n");
  printf("default_basis(lp). Now solve it again...\n");
  press_ret();
  default_basis(lp);
  solve(lp);

  printf("It is possible to give variables and constraints names\n");
  printf("set_row_name(lp,1,\"speed\"); & set_col_name(lp,2,\"money\")\n");
  if (!set_row_name(lp,1,"speed"))
    ERROR();
  if (!set_col_name(lp,2,"money"))
    ERROR();
  print_lp(lp);
  printf("As you can see, all column and rows are assigned default names\n");
  printf("If a column or constraint is deleted, the names shift place also:\n");
  press_ret();
  printf("del_column(lp,1);\n");
  del_column(lp,1);
  print_lp(lp);
  press_ret();

  delete_lp(lp);

/*
  printf("A lp structure can be created and read from a .lp file\n");
  printf("lp = read_LP(\"lp_examples/demo_lag.lp\", TRUE);\n");
  printf("The verbose option is used\n");
  if ((lp = read_LP("lp_examples/demo_lag.lp", TRUE, "test")) == NULL)
    ERROR();
  press_ret();
  printf("lp is now:\n");
  print_lp(lp);

  press_ret();
  printf("solution:\n");
  set_debug(lp, TRUE);
  solve(lp);
  set_debug(lp, FALSE);
  print_objective(lp);
  print_solution(lp, 1);
  print_constraints(lp, 1);
  press_ret();
  printf("You can see that branch & bound was used in this problem\n");

  printf("Now remove the last constraint and use lagrangian relaxation\n");
  printf("del_constraint(lp,6);\n");
  printf("str_add_lag_con(lp, \"1 1 1 0 0 0\", LE, 2);\n");
  del_constraint(lp,6);
  if (!str_add_lag_con(lp, "1 1 1 0 0 0", LE, 2))
    ERROR();
  print_lp(lp);
*/

/*
  printf("Lagrangian relaxation is used in some heuristics. It is now possible\n");
  printf("to get a feasible integer solution without usage of branch & bound.\n");
  printf("Use lag_solve(lp, 0, 30); 0 is the initial bound, 30 the maximum\n");
  printf("number of iterations, the last variable turns the verbose mode on.\n");
  press_ret();
  set_lag_trace(lp, TRUE);
  printf("%d\n",lag_solve(lp, 0, 30));
  printf("The returncode of lag_solve is 6 or FEAS_FOUND. this means that a feasible\n");
  printf("solution has been found. For a list of other possible return values\n");
  printf("see the help file. Print this solution with print_objective, print_solution\n");
  print_objective(lp);
  print_solution(lp, 1);
  print_constraints(lp, 1);

  delete_lp(lp);
*/

  press_ret();

  return(0);
}
Esempio n. 4
0
int MtxLP::addCol(string name, double lb, double ub){
    int i = add_cols(1);
    set_col_name(i, name.data());
    setColBnds(name, lb, ub);
    return i;
}
Esempio n. 5
0
int main(void)
{
  lprec *lp1,*lp2;
  FILE  *input_file;

  printf("lp_solve 2.0 demo by Jeroen J. Dirks ([email protected])\n\n");
  printf("This demo will show most of the features of lp_solve 2.0\n");
  press_ret();
  printf("\nWe start by creating a new problem with 4 variables and 0 constraints\n");
  printf("We use: lp1=make_lp(0,4);\n");
  lp1=make_lp(0,4);
  press_ret();
  printf("We can show the current problem with print_lp(lp1)\n");
  print_lp(lp1);
  press_ret();
  printf("Now we add some constraints\n");
  printf("str_add_constraint(lp1, \"3 2 2 1\" ,LE,4)\n");
  printf("This is the string version of add_constraint. For the normal version\n");
  printf("of add_constraint see the file lpkit.h\n");
  str_add_constraint(lp1, "3 2 2 1", LE, 4);
  print_lp(lp1);
  press_ret();
  printf("str_add_constraint(lp1, \"0 4 3 1\" ,GE,3)\n");
  str_add_constraint(lp1, "0 4 3 1", GE, 3);
  print_lp(lp1);
  press_ret();
  printf("Set the objective function\n");
  printf("str_set_obj_fn(lp1, \"2 3 -2 3\")\n");
  str_set_obj_fn(lp1, "2 3 -2 3");
  print_lp(lp1);
  press_ret();
  printf("Now solve the problem with printf(solve(lp1));\n");
  printf("%d",solve(lp1));
  press_ret();
  printf("The value is 0, this means we found an optimal solution\n");
  printf("We can display this solution with print_solution(lp1)\n");
  print_solution(lp1);
  press_ret();
  printf("The dual variables of the solution are printed with\n");
  printf("print_duals(lp1);\n");
  print_duals(lp1);
  press_ret();
  printf("We can change a single element in the matrix with\n");
  printf("set_mat(lp1,2,1,0.5)\n");
  set_mat(lp1,2,1,0.5);
  print_lp(lp1);
  press_ret();  
  printf("It we want to maximise the objective function use set_maxim(lp1);\n");
  set_maxim(lp1);
  print_lp(lp1);
  press_ret();
  printf("after solving this gives us:\n");
  solve(lp1);
  print_solution(lp1);
  print_duals(lp1);
  press_ret();
  printf("Change the value of a rhs element with set_rh(lp1,1,7.45)\n");
  set_rh(lp1,1,7.45);
  print_lp(lp1);
  solve(lp1);
  print_solution(lp1);
  press_ret();
  printf("We change Var[4] to the integer type with\n");
  printf("set_int(lp1, 4, TRUE)\n");
  set_int(lp1, 4, TRUE);
  print_lp(lp1);
  printf("We set branch & bound debugging on with lp1->debug=TRUE\n");
  lp1->debug=TRUE;
  printf("and solve...\n");
  press_ret();
  solve(lp1);
  print_solution(lp1);	
  press_ret();
  printf("We can set bounds on the variables with\n");
  printf("set_lowbo(lp1,2,2); & set_upbo(lp1,4,5.3)\n");
  set_lowbo(lp1,2,2);
  set_upbo(lp1,4,5.3);
  print_lp(lp1);
  press_ret();
  solve(lp1);
  print_solution(lp1);
  press_ret();
  printf("Now remove a constraint with del_constraint(lp1, 1)\n");
  del_constraint(lp1,1);
  print_lp(lp1);
  printf("Add an equality constraint\n");
  str_add_constraint(lp1, "1 2 1 4", EQ, 8);
  print_lp(lp1);
  press_ret();
  printf("A column can be added with:\n");
  printf("str_add_column(lp1,\"3 2 2\");\n");
  str_add_column(lp1,"3 2 2");
  print_lp(lp1);
  press_ret();
  printf("A column can be removed with:\n");
  printf("del_column(lp1,3);\n");
  del_column(lp1,3);
  print_lp(lp1);
  press_ret();
  printf("We can use automatic scaling with:\n");
  printf("auto_scale(lp1);\n");
  auto_scale(lp1);
  print_lp(lp1);
   press_ret();
  printf("The function mat_elm(lprec *lp, int row, int column) returns a single\n");
  printf("matrix element\n");
  printf("%s mat_elm(lp1,2,3), mat_elm(lp1,1,1); gives\n","printf(\"%f %f\\n\",");
  printf("%f %f\n",mat_elm(lp1,2,3), mat_elm(lp1,1,1));
  printf("Notice that mat_elm returns the value of the original unscaled problem\n");
  press_ret();
  printf("It there are any integer type variables, then only the rows are scaled\n");
  printf("set_int(lp1,3,FALSE);\n");
  printf("auto_scale(lp1);\n");
  set_int(lp1,3,FALSE);
  auto_scale(lp1);
  print_lp(lp1);
  press_ret();
  solve(lp1); 
  printf("print_solution gives the solution to the original problem\n");
  print_solution(lp1);
  press_ret();
  printf("Scaling is turned off with unscale(lp1);\n");
  unscale(lp1);
  print_lp(lp1);
  press_ret();
  printf("Now turn B&B debugging of and simplex tracing on with\n");
  printf("lp1->debug=FALSE, lp1->trace=TRUE and solve(lp1)\n");
  lp1->debug=FALSE;
  lp1->trace=TRUE;
  press_ret();
  solve(lp1);
  printf("Where possible, lp_solve will start at the last found basis\n");
  printf("We can reset the problem to the initial basis with\n");
  printf("reset_basis(lp1). Now solve it again...\n");
  press_ret();
  reset_basis(lp1);
  solve(lp1);
  press_ret();
  printf("It is possible to give variables and constraints names\n");
  printf("set_row_name(lp1,1,\"speed\"); & set_col_name(lp1,2,\"money\")\n");
  set_row_name(lp1,1,"speed");
  set_col_name(lp1,2,"money");
  print_lp(lp1);
  printf("As you can see, all column and rows are assigned default names\n");
  printf("If a column or constraint is deleted, the names shift place also:\n");
  press_ret(); 
  printf("del_column(lp1,1);\n");
  del_column(lp1,1);
  print_lp(lp1);
  press_ret();
  printf("A lp structure can be created and read from a .lp file\n");
  printf("input_file=fopen(\"lp_examples/demo_lag.lp\",\"r\");\n");
  printf("lp2 = read_lp_file(input_file, TRUE);\n");
  printf("The verbose option is used\n");
  input_file = fopen("lp_examples/demo_lag.lp", "r");
  if (input_file == NULL)
    {
      printf("Can't find demo_lag.lp, stopping\n");
      exit(EXIT_FAILURE);
    }
  lp2 = read_lp_file(input_file, TRUE, "test");
  press_ret();
  printf("lp2 is now:\n");
  print_lp(lp2);
  press_ret();
  printf("solution:\n");
  lp2->debug=TRUE; 
  solve(lp2);
  lp2->debug=FALSE;
  print_solution(lp2);
  press_ret();
  printf("You can see that branch & bound was used in this problem\n");
  printf("Now remove the last constraint and use lagrangian relaxation\n");
  printf("del_constraint(lp2,6);\n");
  printf("str_add_lag_con(lp2, \"1 1 1 0 0 0\", LE, 2);\n");
  del_constraint(lp2,6);
  str_add_lag_con(lp2, "1 1 1 0 0 0", LE, 2);
  print_lp(lp2);
  printf("Lagrangian relaxation is used in some heuristics. It is now possible\n");
  printf("to get a feasible integer soltution without usage of branch & bound.\n");
  printf("Use lag_solve(lp2, 0, 40, TRUE); 0 is the initial bound, 30 the maximum\n");
  printf("number of iterations, the last variable turns the verbose mode on.\n");
  press_ret();
  printf("%d\n",lag_solve(lp2, 0, 30, TRUE));
  printf("The returncode of lag_solve is 6 or FEAS_FOUND. this means that a feasible\n");
  printf("solution has been found. For a list of other possible return values\n");
  printf("see \"lpkit.h\". Print this solution with print_solution\n");
  print_solution(lp2);
  press_ret();

  return(0);
}
Esempio n. 6
0
int StateConstraints::fireVectorSize(const PetriNet& net,
									 const MarkVal* m0,
									 const VarVal*) const{
	assert(nPlaces == net.numberOfPlaces());
	assert(nVars == net.numberOfVariables());

	// Create linary problem
	lprec* lp;
	lp = make_lp(0, net.numberOfTransitions());	// One variable for each entry in the firing vector
	assert(lp);
	if(!lp) return false;

	// Set verbosity
	set_verbose(lp, IMPORTANT);

	// Set transition names (not strictly needed)
	for(size_t i = 0; i < net.numberOfTransitions(); i++)
		set_col_name(lp, i+1, const_cast<char*>(net.transitionNames()[i].c_str()));

	// Start adding rows
	set_add_rowmode(lp, TRUE);

	REAL row[net.numberOfTransitions() + 1];
	for(size_t p = 0; p < nPlaces; p++){
		// Set row zero
		memset(row, 0, sizeof(REAL) * net.numberOfTransitions() + 1);
		for(size_t t = 0; t < net.numberOfTransitions(); t++){
			int d = net.outArc(t, p) - net.inArc(p, t);
			row[1+t] = d;
		}

		if(pcs[p].min == pcs[p].max &&
		   pcs[p].max != CONSTRAINT_INFTY){
			double target = pcs[p].min - m0[p];
			add_constraint(lp, row, EQ,  target);
		}else{
			// There's always a min, even zero is interesting
			double target = pcs[p].min - m0[p];
			add_constraint(lp, row, GE,  target);
			if(pcs[p].max != CONSTRAINT_INFTY){
				double target = pcs[p].max - m0[p];
				add_constraint(lp, row, LE,  target);
			}
		}
	}

	// Finished adding rows
	set_add_rowmode(lp, FALSE);

	// Create objective
	memset(row, 0, sizeof(REAL) * net.numberOfTransitions() + 1);
	for(size_t t = 0; t < net.numberOfTransitions(); t++)
		row[1+t] = 1;	// The sum the components in the firing vector

	// Set objective
	set_obj_fn(lp, row);

	// Minimize the objective
	set_minim(lp);

	// Set variables as integer variables
	for(size_t i = 0; i < net.numberOfTransitions(); i++)
		set_int(lp, 1+i, TRUE);

	// Attempt to solve the problem
	int result = solve(lp);

	// Limit on traps to test
	size_t traplimit = nPlaces * OVER_APPROX_TRAP_FACTOR;
	// Try to add a minimal trap constraint
	while((result == OPTIMAL) && traplimit-- < 0){
		memset(row, 0, sizeof(REAL) * net.numberOfTransitions() + 1);
		// Get the firing vector
		get_variables(lp, row);
		// Compute the resulting marking
		MarkVal rMark[net.numberOfPlaces()];
		for(size_t p = 0; p < nPlaces; p++){
			rMark[p] = m0[p];
			for(size_t t = 0; t < net.numberOfTransitions(); t++)
				rMark[p] += (net.outArc(t, p) - net.inArc(p, t)) * (int)row[t];
		}

		// Find an M-trap
		BitField trap(minimalTrap(net, m0, rMark));

		//Break if there's no trap
		if(trap.none()) break;

		// Compute the new equation
		for(size_t t = 0; t < net.numberOfTransitions(); t++){
			row[1+t] = 0;
			for(size_t p = 0; p < nPlaces; p++)
				if(trap.test(p))
					row[1+t] += net.outArc(t, p) - net.inArc(p, t);
		}

		// Add a new row with target as greater than equal to 1
		set_add_rowmode(lp, TRUE);
		add_constraint(lp, row, GE,  1);
		set_add_rowmode(lp, FALSE);

		// Attempt to solve the again
		result = solve(lp);
	}

	int retval = 0;

	if(result != INFEASIBLE){
		get_variables(lp, row);
		for(size_t t = 0; t < net.numberOfTransitions(); t++)
			retval += (int)row[t];
	}

	// Delete the linear problem
	delete_lp(lp);
	lp = NULL;

	// Return true, if it was infeasible
	return retval;
}
Esempio n. 7
0
int main ( int argv, char * argc[] )
{

# if defined ERROR
#  undef ERROR
# endif
# define ERROR() { fprintf(stderr, "Error\n"); exit(1); }
  lprec *lp;
  int majorversion, minorversion, release, build;

#if defined FORTIFY
  Fortify_EnterScope();
#endif

  lp_solve_version(&majorversion, &minorversion, &release, &build);
  printf("lp_solve %d.%d.%d.%d demo\n\n", majorversion, minorversion, release, build);
  printf("This demo will show most of the features of lp_solve %d.%d.%d.%d\n", majorversion, minorversion, release, build);
  press_ret();
  printf("\nWe start by creating a new problem with 4 variables and 0 constraints\n");
  printf("We use: lp=make_lp(0,4);\n");
  if ((lp = make_lp(0,4)) == NULL)
    ERROR();
  press_ret();

  printf("We can show the current problem with print_lp(lp)\n");
  print_lp(lp);
  press_ret();
  printf("Now we add some constraints\n");
  printf("add_constraint(lp, {0, 3, 2, 2, 1}, LE, 4)\n");
  {
    double row[] = {0, 3, 2, 2, 1};
    if (!add_constraint(lp, row, LE, 4))
      ERROR();
  }
  print_lp(lp);
  press_ret();
  printf("add_constraintex is now used to add a row. Only the npn-zero values must be specfied with this call.\n");
  printf("add_constraintex(lp, 3, {4, 3, 1}, {2, 3, 4}, GE, 3)\n");
  {
    int colno[] = {2, 3, 4};
    double row[] = {4, 3, 1};
    if (!add_constraintex(lp, sizeof(colno) / sizeof(*colno), row, colno, GE, 3))
      ERROR();
  }
  print_lp(lp);
  press_ret();
  printf("Set the objective function\n");
  printf("set_obj_fn(lp, {0, 2, 3, -2, 3})\n");
  {
    double row[] = {0, 2, 3, -2, 3};
    if (!set_obj_fn(lp, row))
      ERROR();
  }
  print_lp(lp);
  press_ret();
  printf("Now solve the problem with printf(solve(lp));\n");
  printf("%d",solve(lp));
  press_ret();
  printf("The value is 0, this means we found an optimal solution\n");
  printf("We can display this solution with print_objective(lp) and print_solution(lp)\n");
  print_objective(lp);
  print_solution(lp, 1);
  print_constraints(lp, 1);

  press_ret();
  printf("The dual variables of the solution are printed with\n");
  printf("print_duals(lp);\n");
  print_duals(lp);
  press_ret();
  printf("We can change a single element in the matrix with\n");
  printf("set_mat(lp,2,1,0.5)\n");
  if (!set_mat(lp,2,1,0.5))
    ERROR();
  print_lp(lp);
  press_ret();
  printf("If we want to maximize the objective function use set_maxim(lp);\n");
  set_maxim(lp);
  print_lp(lp);
  press_ret();
  printf("after solving this gives us:\n");
  solve(lp);
  print_objective(lp);
  print_solution(lp, 1);
  print_constraints(lp, 1);
  print_duals(lp);
  press_ret();
  printf("Change the value of a rhs element with set_rh(lp,1,7.45)\n");
  set_rh(lp,1,7.45);
  print_lp(lp);
  solve(lp);
  print_objective(lp);
  print_solution(lp, 1);
  print_constraints(lp, 1);
  press_ret();
  printf("We change %s to the integer type with\n", get_col_name(lp, 4));
  printf("set_int(lp, 4, TRUE)\n");
  set_int(lp, 4, TRUE);
  print_lp(lp);
  printf("We set branch & bound debugging on with set_debug(lp, TRUE)\n");
  set_debug(lp, TRUE);
  printf("and solve...\n");
  press_ret();
  solve(lp);
  print_objective(lp);
  print_solution(lp, 1);
  print_constraints(lp, 1);
  press_ret();
  printf("We can set bounds on the variables with\n");
  printf("set_lowbo(lp,2,2); & set_upbo(lp,4,5.3)\n");
  set_lowbo(lp,2,2);
  set_upbo(lp,4,5.3);
  print_lp(lp);
  press_ret();
  solve(lp);
  print_objective(lp);
  print_solution(lp, 1);
  print_constraints(lp, 1);
  press_ret();
  printf("Now remove a constraint with del_constraint(lp, 1)\n");
  del_constraint(lp,1);
  print_lp(lp);
  printf("Add an equality constraint\n");
  {
    double row[] = {0, 1, 2, 1, 4};
    if (!add_constraint(lp, row, EQ, 8))
      ERROR();
  }
  print_lp(lp);
  press_ret();
  printf("A column can be added with:\n");
  printf("add_column(lp,{3, 2, 2});\n");
  {
    double col[] = {3, 2, 2};
    if (!add_column(lp, col))
      ERROR();
  }
  print_lp(lp);
  press_ret();
  printf("A column can be removed with:\n");
  printf("del_column(lp,3);\n");
  del_column(lp,3);
  print_lp(lp);
  press_ret();
  printf("We can use automatic scaling with:\n");
  printf("set_scaling(lp, SCALE_MEAN);\n");
  set_scaling(lp, SCALE_MEAN);
  print_lp(lp);
  press_ret();
  printf("The function get_mat(lprec *lp, int row, int column) returns a single\n");
  printf("matrix element\n");
  printf("%s get_mat(lp,2,3), get_mat(lp,1,1); gives\n","printf(\"%f %f\\n\",");
  printf("%f %f\n", (double)get_mat(lp,2,3), (double)get_mat(lp,1,1));
  printf("Notice that get_mat returns the value of the original unscaled problem\n");
  press_ret();
  printf("If there are any integer type variables, then only the rows are scaled\n");
  printf("set_scaling(lp, SCALE_MEAN);\n");
  set_scaling(lp, SCALE_MEAN);
  printf("set_int(lp,3,FALSE);\n");
  set_int(lp,3,FALSE);
  print_lp(lp);
  press_ret();
  solve(lp);
  printf("print_objective, print_solution gives the solution to the original problem\n");
  print_objective(lp);
  print_solution(lp, 1);
  print_constraints(lp, 1);
  press_ret();
  printf("Scaling is turned off with unscale(lp);\n");
  unscale(lp);
  print_lp(lp);
  press_ret();
  printf("Now turn B&B debugging off and simplex tracing on with\n");
  printf("set_debug(lp, FALSE), set_trace(lp, TRUE) and solve(lp)\n");
  set_debug(lp, FALSE);
  set_trace(lp, TRUE);
  press_ret();
  solve(lp);
  printf("Where possible, lp_solve will start at the last found basis\n");
  printf("We can reset the problem to the initial basis with\n");
  printf("default_basis(lp). Now solve it again...\n");
  press_ret();
  default_basis(lp);
  solve(lp);

  printf("It is possible to give variables and constraints names\n");
  printf("set_row_name(lp,1,\"speed\"); & set_col_name(lp,2,\"money\")\n");
  if (!set_row_name(lp,1,"speed"))
    ERROR();
  if (!set_col_name(lp,2,"money"))
    ERROR();
  print_lp(lp);
  printf("As you can see, all column and rows are assigned default names\n");
  printf("If a column or constraint is deleted, the names shift place also:\n");
  press_ret();
  printf("del_column(lp,1);\n");
  del_column(lp,1);
  print_lp(lp);
  press_ret();

  write_lp(lp, "lp.lp");

  delete_lp(lp);

  printf("An lp structure can be created and read from a .lp file\n");
  printf("lp = read_lp(\"lp.lp\", TRUE);\n");
  printf("The verbose option is used\n");
  if ((lp = read_LP("lp.lp", TRUE, "test")) == NULL)
    ERROR();
  press_ret();
  printf("lp is now:\n");
  print_lp(lp);

  press_ret();
  printf("solution:\n");
  set_debug(lp, TRUE);
  solve(lp);
  set_debug(lp, FALSE);
  print_objective(lp);
  print_solution(lp, 1);
  print_constraints(lp, 1);
  press_ret();

  delete_lp(lp);

#if defined FORTIFY
  Fortify_LeaveScope();
#endif

    return 0;
}
Esempio n. 8
0
//Execute function
int LPSolveClass::Execute()
{
	/*
	std::cout << "---------------------------------\n";
	std::cout << "objective function\n";
	for (unsigned int i = 0; i < coefficients.size(); i++)
		std::cout << coefficients[i] << "\t";
	std::cout << "\nConstant Value = " << obj_const << std::endl;

	std::cout << "---------------------------------\n";
	std::cout << "Equality Constraints\n";	
	for (unsigned int i = 0; i < A_equ.size(); i++){
		//std::cout << "Row index = " << i << "\t\t";
		for (unsigned int j = 0; j < A_equ[i].size(); j++)
			std::cout << A_equ[i][j] << "\t";
		std::cout << "\n";
	}
	std::cout << "b\n";
	for (unsigned int i = 0; i < b_equ.size(); i++)
		std::cout << b_equ[i] << "\t";
	std::cout << "\n";


	std::cout << "---------------------------------\n";
	std::cout << "InEquality Constraints\n";	
	for (unsigned int i = 0; i < A_inequ.size(); i++){
		//std::cout << "Row index = " << i << "\t\t";
		for (unsigned int j = 0; j < A_inequ[i].size(); j++)
			std::cout << A_inequ[i][j] << "\t";
		std::cout << "\n";
	}
	std::cout << "b\n";
	for (unsigned int i = 0; i < b_inequ.size(); i++)
		std::cout << b_inequ[i] << "\t";
	std::cout << "\n";
	*/

	lprec *lp;
	int Ncol = coefficients.size(), *colno = NULL, j, ret = 0;
	REAL *row = NULL;
	
	/* We will build the model row by row
     So we start with creating a model with 0 rows and n columns */

	lp = make_lp(0, Ncol);
	if (lp == NULL)
		ret = 1;/* couldn't construct a new model... */
		
	if (ret == 0){
		//let us name our variables
		std::string s = "x";
		for (int i = 0; i < Ncol; i++){
			std::stringstream out;
			out << i;
			s = s + out.str();
			char *cpy = new char[s.size()+1] ;
			strcpy(cpy, s.c_str());			
			set_col_name(lp, i+1, cpy);
		}

		/* create space large enough for one row */
		colno = (int *) malloc(Ncol * sizeof(*colno));
    	row = (REAL *) malloc(Ncol * sizeof(*row));
		if ((colno == NULL) || (row == NULL))
      		ret = 2;
	}

	set_add_rowmode(lp, TRUE);
	//add the equation constraints
	if (ret == 0){
		/* makes building the model faster if it is done rows by row */
		if (A_equ.size() > 0){
			for (unsigned int i = 0; i < A_equ.size(); i++){//loop over the rows of equality constraints
				for (unsigned int j = 0; j < A_equ[i].size(); j++){//loop over the columns of equality constraints
					colno[j] = j+1;//add the j-th column to lpsolve
					row[j] = A_equ[i][j];
				}
				/* add the row to lpsolve */
				if(!add_constraintex(lp, A_equ[i].size(), row, colno, EQ, b_equ[i]))
					ret = 2;
			}
		}
	}
	
	//add the inequality constraints
	if (ret == 0){
		/* makes building the model faster if it is done rows by row */
		if (A_inequ.size() > 0){
			for (unsigned int i = 0; i < A_inequ.size(); i++){//loop over the rows of inequality constraints
				for (unsigned int j = 0; j < A_inequ[i].size(); j++){//loop over the columns of inequality constraints
					colno[j] = j+1;//add the j-th column to lpsolve
					row[j] = A_inequ[i][j];
				}
				/* add the row to lpsolve */
				if(!add_constraintex(lp, A_inequ[i].size(), row, colno, LE, b_inequ[i]))
					ret = 3;
			}
		}
	}

	//add the const constraint	
	if (ret == 0){
		if (b_const.size()>0){
			for (unsigned int i = 0; i < b_const.size(); i++){
				if (b_const[i] > 0){
					for (unsigned int j = 0; j < b_const.size(); j++){
						if (i == j){
							colno[j] = j+1;//add the j-th column to lpsolve
							row[j] = 1.0;						
						}				
						else{
							colno[j] = j+1;//add the j-th column to lpsolve
							row[j] = 0.0;
						}
					}
					if(!add_constraintex(lp, b_const.size(), row, colno, EQ, b_const[i]))
						ret = 4;		
				}
			}
		}
	}

	//set the variables to be integer
	if (ret == 0){
		for (int i = 0; i < Ncol; i++)
			set_int(lp, i+1, TRUE);
	}
	
	/* rowmode should be turned off again when done building the model */
	set_add_rowmode(lp, FALSE);	
	//add the objective function
	if (ret == 0){
		//set the objective function
		for (unsigned int i = 0; i < coefficients.size(); i++){
			colno[i] = i+1;
			row[i] = coefficients[i];
		}
		//set the objective in lpsolve
		if(!set_obj_fnex(lp, coefficients.size(), row, colno))
      		ret = 4;
	}

	//set the objective to minimize
	if (ret == 0){
		set_minim(lp);

		/* just out of curioucity, now show the model in lp format on screen */
    	/* this only works if this is a console application. If not, use write_lp and a filename */
    	write_LP(lp, stdout);

		/* I only want to see important messages on screen while solving */
    	set_verbose(lp, IMPORTANT);

    	/* Now let lpsolve calculate a solution */
    	ret = solve(lp);
    	if(ret == OPTIMAL)
      		ret = 0;
    	else
      		ret = 5;
	}

	//get some results
	if (ret == 0){
		/* a solution is calculated, now lets get some results */

    	/* objective value */
    	std::cout << "Objective value: " << get_objective(lp) << std::endl;

		/* variable values */
    	get_variables(lp, row);

		/* variable values */
		variables.resize(Ncol);
		for(j = 0; j < Ncol; j++)
			variables[j] = row[j];

		/* we are done now */
	}
	else{
		std::cout << "The optimal value can't be solved for linear programming, please check the constraints!!\n";
		exit(1);

	}
		
	
	std::cout << "print the result\t # of line segments is \n";
	for (int i = 0; i < Ncol; i++)
		std::cout << "index = " << i << "\t# = " << variables[i] << std::endl;

	/* free allocated memory */
  	if(row != NULL)
    	free(row);
  	if(colno != NULL)
    	free(colno);

	/* clean up such that all used memory by lpsolve is freed */
	if (lp != NULL)
		delete_lp(lp);

	return ret;
}
Esempio n. 9
0
void CLPLpsolve::setFunction(CLPFunction* function)
{
	m_status = 0;

	m_lpFunction = function;
	const int nVars = function->getNumCoefficients();

	// Creates an empty problem with getNumCoefficients variables
	m_env = make_lp(0, nVars);

	if(m_env == NULL)
	{	
		m_status = 1;
	}

	//if(!set_add_rowmode(m_env, FALSE))
	//{
	//	m_status = 1;
	//}
	
	//Allowing memory for rows
	//int * colno = new int[nVars];
    REAL * row= new REAL[nVars + 1];

	//set variables names
	for (int i = 0; i < nVars; ++i)
	{
		int lpIndex = i + 1;
		row[lpIndex] = function->getCoefficients().at(i);
		//colno[i] = lpIndex;

		

		//Determines the type
		switch(function->getIntegers().at(i)) {
			case 'C' :
				m_status = set_unbounded(m_env, lpIndex);
				break;

			case 'B' :
				m_status = set_binary(m_env, lpIndex, TRUE);
				break;

			case 'I' :
				m_status = set_int(m_env, lpIndex, TRUE);
				break;

			case 'S' :
				m_status = set_semicont(m_env, lpIndex, TRUE);
				break;

			default:
				assert(false);
				break;
		}
		
		//Sets upper bound and lower bound
		set_upbo(m_env, lpIndex, function->getUpperBounds().at(i));
		set_lowbo(m_env, lpIndex, function->getLowerBounds().at(i));
		set_col_name(m_env, lpIndex, const_cast<char*>(function->getVarNames().at(i).c_str()));

	}

	//set_obj_fnex(m_env, nVars, row, colno); 
	set_obj_fn(m_env, row);

	// Set the type of the problem (Min or Max)
	switch (function->getType()) {
	case lpMinFunction:
		set_minim(m_env);
		break;

	case lpMaxFunction:
		set_maxim(m_env);
		break;
	}

	if(!set_add_rowmode(m_env, TRUE))
	{
		m_status = 1;
	}
	
	delete [] row;

}
Esempio n. 10
0
double solve_constraints(int this_task)
{
	lprec *lp;
	int numVar = 0, *var = NULL, ret = 0, i, j, k, var_count;
	double *coeff = NULL, lhs,rhs, obj;
	char col_name[10];

	/* Creating a model */
	for(i = 1;i < this_task; i++)
		numVar+=i;	
	lp = make_lp(0, numVar);
	if(lp == NULL)
		ret = 1; /* Couldn't construct a new model */
		
	if(ret == 0) {
		var_count = 1;
		for(i = 1 ; i < this_task; i++){
			for(j = i+1 ; j <= this_task; j++)
			{
				sprintf(col_name, "%dNNP%d_%d", this_task, i, j);
				set_col_name(lp, var_count, col_name);
				var_count++;			
			}
		}
		/* create space large enough for one row(i.e. equation) */
		var = (int *) malloc(numVar * sizeof(*var));
		coeff = (double *) malloc(numVar * sizeof(*coeff));
		if((var == NULL) || (coeff == NULL))
			ret = 2;
	}	
	
	/* add the equations to lpsolve */
	if(ret == 0) {
		set_add_rowmode(lp, TRUE);
		/* --------------------adding EQN-D-------------------- */
		for(j = 2;j <= this_task;j++){
			var_count = 0;
			for(i = 1; i < j; i++){
				sprintf(col_name,"%dNNP%d_%d",this_task, i, j);
				var[var_count] = get_nameindex(lp, col_name, FALSE);
				coeff[var_count] = 1;
				var_count++;
			}

			lhs= 0;
			for(i = 1; i < j; i++)
				lhs+= nnp_min[i][j];
			lhs*= floor(R[this_task]/task[j].p);			
			
			rhs = 0;
			for(i = 1; i < j; i++)
				rhs += nnp_max[i][j];
			rhs *= ceil(R[this_task]/task[j].p);
			
			if(!add_constraintex(lp, var_count, coeff, var, GE, lhs))
				ret = 3;
			if(!add_constraintex(lp, var_count, coeff, var, LE, rhs))
				ret = 3;			
		}
	}
	
	if(ret == 0) {	
		/* --------------------adding EQN-E-------------------- */
		for(k = 2;k <= this_task;k++)
		{			
			var_count = 0;
			for(j = 2; j <= k; j++){
				for(i = 1; i < j; i++){
					sprintf(col_name,"%dNNP%d_%d",this_task, i, j);
					var[var_count] = get_nameindex(lp, col_name, FALSE);
					coeff[var_count] = 1;
					var_count++;
				}
			}
			
			rhs = 0;
			for(i = 1; i < k; i++)
				rhs += ceil(R[this_task]/task[i].p);
			if(!add_constraintex(lp, var_count, coeff, var, LE,rhs))
				ret = 3;
		}
	}
	
	if(ret == 0) {
		/* ------------------adding EQN-G & H------------------ */
		for(j = 2; j <= this_task ; j++){
			for(i = 1; i < j; i++){
				lhs= floor(R[this_task]/task[j].p) * nnp_min[i][j];
				sprintf(col_name,"%dNNP%d_%d",this_task, i, j);
				var[0] = get_nameindex(lp, col_name, FALSE);
				coeff[0] = 1;
				if(!add_constraintex(lp, 1, coeff, var, GE, lhs))
					ret = 3;
				
				rhs = min(ceil(R[this_task]/task[i].p), ceil(R[this_task]/task[j].p) * ceil(R[j]/task[i].p), ceil(R[this_task]/task[j].p) * nnp_max[i][j]);
				if(!add_constraintex(lp, 1, coeff, var, LE,rhs))
					ret = 3;
			}
		}
	}
	
	if(ret == 0) {
 		/* --------------------adding EQN-I-------------------- */
		for(i = 1; i < this_task; i++){
			var_count = 0;
			for(j = i+1; j <= this_task; j++){
				sprintf(col_name,"%dNNP%d_%d",this_task, i, j);
				var[var_count] = get_nameindex(lp, col_name, FALSE);
				coeff[var_count] = 1;
				var_count++;				
			}
			rhs = ceil(R[this_task]/task[i].p);
			if(!add_constraintex(lp, var_count, coeff, var, LE,rhs))
				ret = 3;
		}
	}
		
	set_add_rowmode(lp, FALSE);
	if(ret == 0) {
		/* -----------------set the objective----------------- */
		var_count = 0;
		for(i = 1 ; i < this_task; i++){
			for(j = i+1 ; j<= this_task; j++){
				sprintf(col_name,"%dNNP%d_%d",this_task, i, j);
				var[var_count] = get_nameindex(lp, col_name, FALSE);
				coeff[var_count] = get_f(this_task, i, j);
				var_count++;
			}			
		}
		if(!set_obj_fnex(lp, var_count, coeff, var))
			ret = 4;
		set_maxim(lp);
		write_LP(lp, stdout);
		set_verbose(lp, IMPORTANT);
		ret = solve(lp);
		if(ret == OPTIMAL)
			ret = 0;
		else
			ret = 5;
	}
	if(ret == 0) {
		obj = get_objective(lp);
		/* Displaying calculated values */		
		/* variable values */
		printf("\nVariable values:\n");
		get_variables(lp, coeff);
		printf("\n");
		for(j = 0; j < numVar; j++)
			printf("%s: %f\n", get_col_name(lp, j + 1), coeff[j]);		
		/* objective value */
		printf("\nObjective value: %f\n\n", obj);
	}
	printf("LP ERROR = %d\n\n", ret);
	
	/* free allocated memory */
	if(coeff != NULL)
		free(coeff);
	if(var != NULL)
		free(var);
	if(lp != NULL) 		
		delete_lp(lp);
	
	return ret == 0 ? obj : 0;
}
Esempio n. 11
0
    int  calculate (IN  int nCols /* variables in the model */,
                    IN  int nRows,
                    IN  double** rows,
                    IN  double*  rights,
                    IN  double*  objectives,
                    OUT int* answer,
                    IN  int verbose)
    {
      lprec *lp;
      int result = 0;

      char *str = NULL;
      int *colno = NULL;
      double *row = NULL;

      /*  We will build the model row by row
       *  So we start with creating a model
       *  with 0 rows and 2 columns
       */
      if ( !(lp = make_lp (0, nCols)) )
      { 
        /* couldn't construct a new model... */
        result = 1;
        goto RESULT;
      }

      if ( !(str = (char*) malloc ((log10 (nCols) + 10) * sizeof (*str))) )
      {
        result = 2;
        goto RESULT;
      }

      /*  let us name our variables. Not required, 
       *  but can be useful for debugging
       */
      for ( int i = 1; i <= nCols; ++i )
      {       
        str[0] = 't';
        _itoa (i, str + 1, 10);

        set_col_name (lp, i, str);
        // set_int (lp, i, TRUE);
      }

      /* create space large enough for one row */
      colno = (int   *) malloc (nCols * sizeof (*colno));
      row   = (double*) malloc (nCols * sizeof (*row));

      if ( (colno == NULL) || (row == NULL) )
      {
        result = 2;
        goto RESULT;
      }

      for ( int j = 0; j < nCols; ++j )
      { colno[j] = j + 1; /* (j + 1) column */ }

      /* makes building the model faster if it is done rows by row */
      set_add_rowmode (lp, TRUE);
      
      for ( int i = 0; i < nRows; ++i )
      {
        // /* construct j row */
        // for ( int j = 0; j < nCols; ++j )
        // { row[j] = ??? ; }

        /* (210 * t2 + 156 * t3 == 0.0178) */
        /* (230 * t2 + 160 * t3 == 0.0176) */

        /* add the row to lp_solve */
        if ( !add_constraintex (lp, nCols, rows[i], colno, EQ, rights[i]) )
        {
          result = 3;
          goto RESULT;
        }
      }

      /* rowmode should be turned off again when done building the model */
      set_add_rowmode (lp, FALSE); 

      // /* set the objective function  */
      // for ( int j = 0; j < nCols; ++j )
      // { row[j] = objectives[j]; }

      /* (t1 + t2 + t3 + t4) */

      /* set the objective in lp_solve */
      if ( !set_obj_fnex (lp, nCols, objectives, colno) )
      {
        result = 4;
        goto RESULT;
      }
      
      /* set the object direction to maximize */
      set_minim (lp);

      if ( verbose )
      {
        /* just out of curioucity, now show the model in lp format on screen */
        /* this only works if this is a console application. If not, use write_lp and a filename */
        write_LP (lp, stdout);
        /* write_lp(lp, "model.lp"); */
      }
      
      /* I only want to see important messages on screen while solving */
      set_verbose (lp, IMPORTANT);
      
      /* Now let lpsolve calculate a solution */
      result = solve (lp);
      if ( result == OPTIMAL )
      { result = 0; }
      else
      {
        result = 5;
        goto RESULT;
      }

      /*  a solution is calculated,
       *  now lets get some results
       */
      if ( verbose )
      {
        /* objective value */
        printf ("Objective value: %f\n", get_objective (lp));
      }

      /* variable values */
      get_variables (lp, row);
      for ( int j = 0; j < nCols; j++ )
      {
        if ( verbose )
          printf ("%s: %f\n", get_col_name (lp, j + 1), row[j]);
        
        answer[j] = row[j];
      }
      /* we are done now */

RESULT:;
      /* free allocated memory */
      if ( str != NULL )free (str);
      if ( row != NULL ) free (row);
      if ( colno != NULL ) free (colno);

      if ( lp != NULL )
      {
        /* clean up such that all used memory by lpsolve is freed */
        delete_lp (lp);
      }

      return result;
    }
Esempio n. 12
0
int demo()
{
    lprec *lp;
    int Ncol, *colno = NULL, j, ret = 0;
    REAL *row = NULL;

    /* We will build the model row by row
       So we start with creating a model with 0 rows and 2 columns */
    Ncol = 2; /* there are two variables in the model */
    lp = make_lp(0, Ncol);
    if(lp == NULL)
        ret = 1; /* couldn't construct a new model... */

    if(ret == 0) {
        /* let us name our variables. Not required, but can be useful for debugging */
        set_col_name(lp, 1, "x");
        set_col_name(lp, 2, "y");

        /* create space large enough for one row */
        colno = (int *) malloc(Ncol * sizeof(*colno));
        row = (REAL *) malloc(Ncol * sizeof(*row));
        if((colno == NULL) || (row == NULL))
            ret = 2;
    }

    if(ret == 0) {
        set_add_rowmode(lp, TRUE);  /* makes building the model faster if it is done rows by row */

        /* construct first row (120 x + 210 y <= 15000) */
        j = 0;

        colno[j] = 1; /* first column */
        row[j++] = 120;

        colno[j] = 2; /* second column */
        row[j++] = 210;

        /* add the row to lpsolve */
        if(!add_constraintex(lp, j, row, colno, LE, 15000))
            ret = 3;
    }

    if(ret == 0) {
        /* construct second row (110 x + 30 y <= 4000) */
        j = 0;

        colno[j] = 1; /* first column */
        row[j++] = 110;

        colno[j] = 2; /* second column */
        row[j++] = 30;

        /* add the row to lpsolve */
        if(!add_constraintex(lp, j, row, colno, LE, 4000))
            ret = 3;
    }

    if(ret == 0) {
        /* construct third row (x + y <= 75) */
        j = 0;

        colno[j] = 1; /* first column */
        row[j++] = 1;

        colno[j] = 2; /* second column */
        row[j++] = 1;

        /* add the row to lpsolve */
        if(!add_constraintex(lp, j, row, colno, LE, 75))
            ret = 3;
    }

    if(ret == 0) {
        set_add_rowmode(lp, FALSE); /* rowmode should be turned off again when done building the model */

        /* set the objective function (143 x + 60 y) */
        j = 0;

        colno[j] = 1; /* first column */
        row[j++] = 143;

        colno[j] = 2; /* second column */
        row[j++] = 60;

        /* set the objective in lpsolve */
        if(!set_obj_fnex(lp, j, row, colno))
            ret = 4;
    }

    if(ret == 0) {
        /* set the object direction to maximize */
        set_maxim(lp);

        /* just out of curioucity, now show the model in lp format on screen */
        /* this only works if this is a console application. If not, use write_lp and a filename */
        write_LP(lp, stdout);
        /* write_lp(lp, "model.lp"); */

        /* I only want to see important messages on screen while solving */
        set_verbose(lp, IMPORTANT);

        /* Now let lpsolve calculate a solution */
        ret = solve(lp);
        if(ret == OPTIMAL)
            ret = 0;
        else
            ret = 5;
    }

    if(ret == 0) {
        /* a solution is calculated, now lets get some results */

        /* objective value */
        printf("Objective value: %f\n", get_objective(lp));

        /* variable values */
        get_variables(lp, row);
        for(j = 0; j < Ncol; j++)
            printf("%s: %f\n", get_col_name(lp, j + 1), row[j]);

        /* we are done now */
    }

    /* free allocated memory */
    if(row != NULL)
        free(row);
    if(colno != NULL)
        free(colno);

    if(lp != NULL) {
        /* clean up such that all used memory by lpsolve is freed */
        delete_lp(lp);
    }

    return(ret);
}