Whitney theorem for copositive approximation in

Abstract

In this research, we have important results about finding the relationship between the best approximation degree and the so called modulus ( or Sendov- Popov modulus ) of order  in the space , and the polynomial is copositive with the function  at the points in an interval , and also found assessment between the best approximation degree  by algebraic polynomial of degree  , and the modulus of smoothness of degree , to the function  ,  .