example_contour.m

clc; clear all;

% Plot the feasible space for the Masonry LP
% max Z = 140*x1 + 160*x2
% subject to:
% 2*x1 + 4*x2 <= 28
% 5*x1 + 5*x2 <= 50
% x1 <= 8
% x2 <= 6
% x1, x2 >= 0

% general range for x values
x = 0:1:10;

% contour
[X1,X2] = meshgrid(x,x);
Z = 140*X1 + 160*X2;
contour(X1,X2,Z,25);

% constraint lines
hold on;
plot(x, (28 - 2*x)/4, 'k', 'linewidth', 2);
plot(x, (50 - 5*x)/5, 'k', 'linewidth', 2);
plot(8*ones(length(x)), x, 'k', 'linewidth', 2);
plot(x, 6*ones(length(x)), 'k', 'linewidth', 2);

xlabel('Amount of HYDIT (tons/wk)');
ylabel('Amount of FILIT (tons/wk)');
title('Masonry LP problem');
hcb = colorbar;
set(get(hcb,'ylabel'),'String', 'Profit Z (millions $)');