IJSRP, Volume 11, Issue 6, June 2021 Edition [ISSN 2250-3153]
Abdulmtalb Hussen, Abdelbaset Zeyani
The classical Fejer-Riesz Theorem has many applications in various mathematical fields. This survey paper presents this theorem in several versions: 1) with operatorvalued functions as coefficients, 2) in 2 2 matrix form, and 3) in the multivariate case. The main ideas of the proofs are sketched.