iamboorrito/simplex-method

A learning tool that performs the simplex method.

Simplex-Method

A learning tool that performs the simplex method (Phase 2 of the Two-Phase Algorithm). This requires your tableau be in canonical form, has a basic variable in each row, to guarantee termination.

Creates a window containing grid cells representing the input simplex tableau. There are buttons for single-step iteration, iteration to completion, resizing, and undoing. It's still a work in progress, so I expect bugs to arise as it gets used more.

The editor also supports common math functions through mXparser.

Here, the program solves the problem:

Minimize -4X1 - 6X2

Subject to 

 -X1 +   X2 + S1       = 11

  X1 +   X2 +     S2   = 27

2 X1 + 5 X2 +       S3 = 90

X1, X2, S1, S2, S3 >= 0

Where S1, S2, S3 are slack variables added to put this in standard form.

Duality

This program now supports dual programs! You must put it into the form

Minimize f(x,...)

Subject to

Ax >= b

Example:

Minimize 12 X1 + 15 X2

Subject to

60 X1 + 50 X2 >= 200
10 X1 +  3 X2 >= 19
11 X1 + 13 X2 >= 8
X1, X2 >= 0

simplex-method's Issues

Need better undo/redo structure

The current structure saves too much data. Should only need to save changes to the table or tableau and not save copies. Maybe create an enum with the different types of events and process undo/redo actions off of the returned event type.

Better History Stack

Current implementation is pretty much hacked through and should be redesigned to be part of the Frame and not the Tableau Object.

Implement row and column insertion for GUI

It should already be done in Tableau.java but it needs to be added to interface.

Need to ensure Tableau and JeksTable sync properly.

Does not work correctly for some input, I think the constraint column might not be added to the Tableau. Also, the gray background color seems to disappear when iteration begins.

Add basic algebraic options as input

It would be nice to allow simple expressions as input, especially division since typing 1/3 as 0.333 etc is too cumbersome.

Subclass RXTable or add algorithm to LPFrame to remove Tableau storage.

This project started out as a terminal program using the Tableau class to implement the Simplex Algorithm, but now that it is graphical the table model stores the same data as the underlying representation (thanks to a functioning MathEditor). This makes the Tableau class redundant and should be removed in future versions.

Show solution as tuple in outputField

It would be nice to have a method which looks through the table to find the solution and display it.

Limit Algorithm and Table connection

I want to have the algorithm be as separate as possible from the table and any graphics code. Then I could add more algorithms.

Add set size button

I would like to add a button which displays a dialog, maybe JOptionPane's internal message, and resizes the table/tableau accordingly.