equation = {@(x,u) u' + 2*u + 5*volt(u), @(x) 1};
domain = [0 10];
condition = @(u) u(0);
options = tau.settings('degree', 64);
problem = tau.problem(equation, domain, condition, options);
yn = tau.solve(problem);
subplot(1,2,1)
plot(yn);
subplot(1,2,2)
u = linspace(yn);
semilogy(u, abs(yn(u)-0.5.*exp(-u).*sin(2.*u)));
title('Absolute error')
