The approximating function is: M ψ(z, t) ≈ψˆ(z, t) = ∑ NJ(z)ψJ(t) J=1 (14) where NJ(z) and ψJ(t) are linear Lagrange basis functions and nodal values of ψ at time t, respectively. The method of weighted residuals is used to set the criteria to solve for the ...