function y=U(x,t)
%
% Calculates solution of heat equation
L = 10;
alpha = sqrt(1.14); % for copper
T0 = 100;
infinity=100; % a large number!
if t==0
    y=T0;
else
    y=0;
    for n=1:infinity
        y=y +((1-(-1)^n)/n)*sin(n*pi*x/L)*exp(-(n*pi*alpha/L)^2*t);
    end
    y=y*2*T0/pi;
end