| 
         
        
           |  |  |  |   
          |  | Volume 3, Issue 1, Article 10 |  |   
          |  |  |  |  |  |  | Some Results on $L^1$ Approximation of the $r$-th Derivate of Fourier Series
 
 
 |   
          |  |  | Authors: | Zivorad Tomovski, |  |   
          |  |  | Keywords: | $L^1$-approximation, Fourier series, Sidon-Telyakovskii class, Telyakovskii inequality. |  |   
          |  |  | Date Received: | 22/09/99 |  |   
          |  |  | Date Accepted: | 18/10/01 |  |   
          |  |  | Subject Codes: | 26D15,42A20 |  |   
          |  |  | Editors: | Alexander G. Babenko, |  |   
          |  |   
          |  |  |  |  |  |   
          |  |  | Abstract: |  In this paper we obtain the conditions for  -convergence of the  -th derivatives of the cosine and sine trigonometric series. These results are extensions of corresponding Sidon's and Telyakovskii's theorems for trigonometric series (case:  ). 
 |   
          |  |  |  |  |  |   
          |  |  |  |  |  |   
          |  |  |  |  |  |  |