MATLAB Feasible Region Plot

try
    A=[-1 -2; -4 -3; 1 0 ; 0 1];
    b = [ -40; -120; 0; 0];
    plotregion(A,b);
    hold on;
    x=1:30;
    y = (100 - 4*x)/5;
    plot(x,y,'k--','LineWidth',2)
    y = (136 - 4*x)/5;
    plot(x,y,'k','LineWidth',2)
catch ME
    if(strcmp(ME.identifier, 'MATLAB:UndefinedFunction'))
        rethrow(ME);
        display('Please download PlotRegion from MATLAB File Exchange')
        display('Link: http://www.mathworks.com/matlabcentral/fileexchange/9261-plot-2d3d-region')
    end
end