November 2017
Intermediate to advanced
306 pages
6h 24m
English
For the convenience of reference, we list a number of classical results in this section.
THEOREM A.1.– (Abel’s Theorem) If the series
is convergent with (finite) value R, then the series

converges uniformly in s ∈ [0, 1] and
If an ≥ 0 for all n and R = ∞, then limn → ∞ R(s) = ∞.
With the same notation as in the previous theorem, the following statement is valid.
THEOREM A.2.– (Tauber’s Theorem) If

and there exists a finite limit
then the sum
is convergent and

DEFINITION A.1.– A positive function L(t), t ≥ t0 is called slowly varying at infinity if

PROPOSITION A.1.– A function L(t) is slowly varying at infinity if and only if it may be represented in the form:
where a(t) → ...