Best approximation of holomorphic functions from Hardy space in terms of Taylor coefficients
F G Abdullayev, G A Abdullayev, V V Savchuk
We describe the set of holomorphic functions from the Hardy space Hq, 1 ≤ q ≤ ∞, for which the best polynomial approximation En( f )q is equal to | f (n)(0)|/n!