By Yamal 
The Revised Simplex Method is an efficient algorithm used in linear programming to solve optimization problems. It is a variation of the original Simplex Method, designed to improve computational efficiency, particularly for large problems with many variables and constraints. Here’s a breakdown of the Revised Simplex Method and how it works:
- Overview of Linear Programming
Linear programming involves maximizing or minimizing a linear objective function subject to a set of linear constraints. The Simplex Method is one of the foundational algorithms used to solve these problems, iterating through feasible solutions at the vertices of the feasible region until it finds the optimal solution.
- Limitations of the Standard Simplex Method
While the standard Simplex Method is effective, it can become inefficient with larger problems due to the need to maintain the entire tableau, which contains all variables and constraints. This can lead to high memory usage and slower computation times. The Revised Simplex Method addresses these issues by focusing on the essential components of the problem.
- Key Concepts of the Revised Simplex Method
– Basic and Non-Basic Variables: In the Revised Simplex Method, variables are categorized as basic or non-basic. Basic variables correspond to the active constraints in the solution, while non-basic variables are those not currently in the solution. The method works with a reduced set of variables to streamline calculations.
– Basic Feasible Solution (BFS): The method starts with an initial basic feasible solution, which is often derived from a feasible corner point of the constraint set. This initial point serves as the starting point for optimization.
- Matrix Representation
The Revised Simplex Method uses matrix operations to simplify calculations. Instead of maintaining an entire tableau, it utilizes matrices to represent the objective function, constraints, and basic/non-basic variables. This allows for efficient updates during iterations.
– Simplex Tableau Reduction: The computations involve adjusting the basis matrix and the cost coefficients of non-basic variables more directly than in the traditional tableau approach.
- Iterative Process
The Revised Simplex Method proceeds through iterations as follows:
– Entering Variable: Identify a non-basic variable that will enter the basis (the one that will increase and can potentially improve the objective function).
– Leaving Variable: Determine which basic variable will leave the basis, usually dictated by the constraint that will be violated first (using the ratio test).
– Update: Perform pivoting operations to update the basis matrix and the corresponding objective function coefficients.
- Optimality Check
Once the algorithm identifies a new BFS, it checks for optimality. If there are no non-basic variables with positive coefficients that can enter the basis (for maximization problems), the current solution is optimal.
- Advantages of the Revised Simplex Method
– Efficiency: By working with a reduced set of variables, the Revised Simplex Method significantly lowers computational overhead, making it faster and more suitable for large-scale problems.
– Numerical Stability: It often exhibits improved numerical stability due to its reliance on matrix operations rather than maintaining extensive tabular data.
- Conclusion
The Revised Simplex Method is a powerful tool in linear programming that optimizes computational efficiency, especially for large problems. By focusing on essential components and utilizing matrix representation, it streamlines the optimization process, making it suitable for more complex applications in various fields such as operations research, economics, and engineering. Understanding this method can enhance practitioners’ ability to tackle real-world optimization challenges effectively.