The  equivalent theorems for best approximation in weighted spaces

esraa salim; Alaa  Adnan Auad

doi:10.47831/mjpas.v4i3.401

Authors

esraa salim Department of Mathematics, College of Education for Pure Sciences, University of Anbar, Anbar, Iraq
Alaa Adnan Auad Department of mathematics, College of Education for pure science, University of Anbar

DOI:

https://doi.org/10.47831/mjpas.v4i3.401

Abstract

The modulus of smoothness is used to demonstrate the direct and inverse trigonometric
polynomials estimation theorem in weighted space with the degree of best approximation of
unbounded functions. Also, we approximate of derivative function by derivative of
trigonometric polynomials in weighted spaces. Moreover, an unbounded function is better
the degree of best approximation for derivative functions in same space.