NEAR CIRCULARITY AND ZEROS OF THE ERROR FUNCTION FOR CHEBYSHEV APPROXIMATION 0N A DISK

1. Introduction A classical characterization of the best Chebyshev polynomialapproximation to a real continuous function on an interval [a, b]is the equioscillation property of the optimal error function.Consequently, when approximating f∈C [a, b] by polynomials of