I think not, because the initial conditions are probably going to be in the form u(t=0,x)=f(x) and \frac{∂u}{∂t}(t=0,x)=g(x), because it is an infinite string (no boundary conditions). But if I we separate variables (i.e. u(x,t)=X(x)*T(t)), we have to put a single value and not a function for...