Hi, in the first example, your feasible set is just one point (the one that fulfills the 3 equations) and thus there is only this one point which can maximize the objective function. In the second case, the feasible set is a line. But the simplex algorithm tries to find an optimizing value of the objective on a convex polyhedron. So the simplex function may be inappropriate to find all feasible solutions.
HTH Armin ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.