**MSC:**- 41A05 Interpolation, See also {42A15 and 65D05}
- 41A10 Approximation by polynomials, {For approximation by trigonometric polynomials, See 42A10}

la Vallee Poussin operators in Fourier series, which preserve polynomial

of a certain degree, but are defined in terms of the values of the

function rather than its Fourier coefficients.