Primal Simplex Optimizer
CPLEX's Primal Simplex Optimizer also can effectively solve a wide variety of linear programming problems with its default parameter settings. With recent advances in the dual simplex method, the primal simplex method is no longer the obvious choice for a first try at optimizing a linear programming problem. However, this method will sometimes work better on problems where the number of variables exceeds the number of constraints significantly, or on problems that exhibit little variability in the cost coefficients. Few problem exhibit poor numerical performance in both primal and dual form. Consequently, if you have a problem where numerical difficulties occur when you use the dual simplex optimizer, then consider using the primal simplex optimizer instead.
