%% Adjust Base Value of Area Graph
% By default, |area| uses the _y_-axis as the base value. Change the base
% value by setting the |basevalue| input argument to -4.

% Copyright 2015 The MathWorks, Inc.

Y = [1, 5, 3;
     3, 2, 7;
     1, 5, 3;
     2, 6, 1];
figure
basevalue = -4;
area(Y,basevalue) 