On trigonometric-like decompositions of functions with respect to the   cyclic group of order n
  The cyclic group labeled family of quasi-projection operators is used for investigation of decomposition of functions with respect to the cyclic group of order n . Series of new identities thus arising are demonstrated and new perspectives for further investigation are indicated as for example in the case of q-extended special polynomials. 
A. K. Kwasniewski, B. K. Kwasniewski