“…By using Theorem 5.3 for a nm in Patel et al 67 of Equation ( 53), we have Thus, ||u N (x, t)−u N (x, t)|| 2 2 → 0 as N, N → ∞, that this shows the sequence of partial sums u N (x, t) is a Cauchy sequence in Hilbert space L 2 ([0, 1] × [0, 1]) and it converges to say Ξ. To complete the proof, we show that u(t) = Ξ, and then we have…”