%  Produces four plots of different density functions in a 2x2 table.  
%  The exponential, gamma, beta, and normal densities are shown.  

%  Opens a figure opject and sets the borders.
figure
set(gcf, 'Position', [200, 100, 1100, 800])

%  Set some style parameters.  
fontsize = 18;
linewidth = 2;
% Using '-k' in plot calls uses a solid black line rather than the default blue.

%  Plot the exponential density. 
x = 0:(8/500):8;
exponentialDensity = exppdf(x, 1);
subplot(2, 2, 1)
plot(x, exponentialDensity, '-k', 'LineWidth', linewdith)
set(gca, 'Box','off', 'FontSize', fontsize, ...
    'XTick', 0:2:8, 'YTick', [], 'TickDir', 'out')

%  Plot the gamma density.  
x = 0:(10/500):10;
gammaDensity = gampdf(x, 2, 1);
subplot(2, 2, 2)
plot(x, gammaDensity, '-k', 'LineWidth', linewidth)
set(gca, 'Box','off', 'FontSize', fontsize, ...
    'XTick', 0:2:10, 'YTick', [], 'TickDir', 'out')

%  Plot the beta density.  
x = 0:(1/500):1;
betaDensity = betapdf(x, 6, 6);
subplot(2, 2, 3)
plot(x, betaDensity, '-k', 'LineWidth', linewidth)
set(gca, 'Box','off', 'FontSize', fontsize, ...
    'XTick', 0:0.2:1, 'YTick', [], 'TickDir', 'out')

%  Plot the normal density.  
x = -4:(8/500):4;
normalDensity = normpdf(x, 0, 1);
subplot(2, 2, 4)
plot(x, normalDensity, '-k', 'LineWidth', linewdith)
set(gca, 'Box','off', 'FontSize', fontsize, ...
    'XTick', -4:2:4, 'YTick', [], 'TickDir', 'out')