Let R > 1 and denote by ℰR
is a polynomial of degree at most n such that
then (; also see [13, p. 337] and [9, p. 158, Prob. No. 270])
The standard proof of this well known result runs as follows. The function
is entire and in view of (2) we have
Hence by the maximum modulus principle
which is clearly equivalent to (3).