Approximation of functions by (C,2)(E,1) product summability method of Fourier series

Various investigators such as Leindler [10], Chandra [1], Mishra et al. [7], Khan [11], Kushwaha [6] have determined the degree of approximation of 2 pai-periodic functions belonging to generalized Lipschitz class of functions through trigonometric Fourier approximation using different summability means. Recently H.K. Nigam [12] has determined that the Fourier series is summable under the summability means (C,2)(E,1) but he did not find the degree of approximation of function belonging to various classes. In this paper a theorem concerning the degree of approximation of function belonging to class by (C,2)(E,1) product summability method of Fourier series has been established which in turn generalizes the result of H. K. Nigam [12]