The OPTLP procedure provides four methods of solving linear programs (LPs). A linear program has the following formulation:
where



is the vector of decision variables 



is the matrix of constraints 



is the vector of objective function coefficients 



is the vector of constraints righthand sides (RHS) 



is the vector of lower bounds on variables 



is the vector of upper bounds on variables 
The following LP solvers are available in the OPTLP procedure:
primal simplex solver
dual simplex solver
network simplex solver
interior point solver
The primal and dual simplex solvers implement the twophase simplex method. In phase I, the solver tries to find a feasible solution. If no feasible solution is found, the LP is infeasible; otherwise, the solver enters phase II to solve the original LP. The network simplex solver extracts a network substructure, solves this using network simplex, and then constructs an advanced basis to feed to either primal or dual simplex. The interior point solver implements a primaldual predictorcorrector interior point algorithm.
PROC OPTLP requires a linear program to be specified using a SAS data set that adheres to the MPS format, a widely accepted format in the optimization community. For details about the MPS format see Chapter 15: The MPSFormat SAS Data Set.
You can use the MPSOUT= option to convert typical PROC LP format data sets into MPSformat SAS data sets. The option is available in the LP, INTPOINT, and NETFLOW procedures. For details about this option, see Chapter 5: The LP Procedure in SAS/OR 12.3 User's Guide: Mathematical Programming Legacy Procedures, Chapter 4: The INTPOINT Procedure in SAS/OR 12.3 User's Guide: Mathematical Programming Legacy Procedures, and Chapter 6: The NETFLOW Procedure in SAS/OR 12.3 User's Guide: Mathematical Programming Legacy Procedures.