At upper left there is a large graphing window. A cursor rollover produces a readout of the \(x\) and \(y\) coordinates at lower right.

In the window, the range in which a family of linear inequalities is satisfied is shaded gray. Initially there are two inequalities: \(x \geq 0\) and \(y \geq 0\). Up to six additional inequalities may be added as follows: Click and drag to position a point, represented by a red dot, and drop it by releasing the mousekey. Click and drag again to produce a second point. The line through them is drawn in cyan, and the equation of the line is displayed at right. Releasing the mousekey drops the line. Now a rolling the mouse over the window will convert the equality in to an inequality satisfied by the position of the cursor, and clicking on a point on the plane will specify the direction of the inequality.

To remove a constraint, select [Remove Constraint] and then click on a point near to the selected constraint line.

Sliders at lower right control the coefficients \(a\) and \(b\) in the objective function \(ax + by\). When not both are zero, a \(c\) slider controls the value of the objective function, and the line \(ax + by = c\) is drawn in yellow. The portion of the line meeting the constraint region is made bolder, and if the intersection is nonempty the constraint region changes to a paler gray.

© 2015 H. Miller and H. Petrow