“…Theorem Suppose y n ( x , t ) is the approximate solution of the problem (1) in space and y ( x , t ) is the exact solution then , where ( x , t ) ∈ D and ∥ y ( x , t ) − y n ( x , t )∥ ∞ = max ( x , t ) ∈ D = | y ( x , t ) − y n ( x , t )| and ∥ ∂ x ∂ t y ( x , t ) − ∂ x ∂ t y n ( x , t )∥ ∞ = max ( x , t ) ∈ D = | ∂ x ∂ t y ( x , t ) − ∂ x ∂ t y n ( x , t )| and C 1 , C 2 , C 3 , C 4 are positive constants , , and . n = n 1 × n 2 where is number of collocation points in region D . Proof For more details refer to [28–32]. In each [ x i , x i + 1 ] × [ t j , t j + 1 ] ⊂ D we have, …”