On the degree of approximation to periodic functions by a trigonometric spline convolution operator (Q581795)

The author defines a trigonometrie spline convolution operator \(\sigma_ n^ m(f,x)\) and shows that for \(f\in C_{2\pi}\), \(\sigma_ h^ m(f;x)\to f(x)\) uniformly on R as mh\(\to 0\) and \((m+1)h<\pi\), where \(w_ f\) denotes the modulus of continuity of f.