load temperature 
Tin = 72;
L = 2;
x = linspace(0,L,24); 

% create replicated data to match each
% 'temp' value to 'x'
ttemp = repmat(temp,1,length(x));
xx = repmat(x,24,1);


% calculate the value of Tx (the gradient)
Tx = (Tin - ttemp) .* xx./L + ttemp;
% create a surface of the data
surf(xx,time,Tx)

xlabel('Distance through the wall (Ft)')
ylabel('Time (24 hour clock)')
zlabel('Temperature ( T_x )')
title('\bf{Temperature gradient through a wall}')
