Fejer and Suffridge polynomials in the delayed feedback control theory
  A remarkable connection between optimal delayed feedback control (DFC) and complex polynomial mappings of the unit disc is established. The explicit form of extremal polynomials turns out to be related with the Fejer polynomials. The constructed DFC can be used to stabilize cycles of one-dimensional non-linear discrete systems. 
Dmitriy Dmitrishin, Anna Khamitova, Anatolii Korenovskyi and Alex   Stokolos
math.DS