WOLFRAM|DEMONSTRATIONS PROJECT

Cesàro Summation

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partial sums of Cesàro series
The Cesàro sum of an infinite series
∞
∑
k=0
f
k
is given by
lim
m∞
1
m+1
m
∑
n=0

n
∑
k=0
f
k

, provided that this limit exists. If a convergent series has sum
S
, then it is Cesàro summable and has Cesàro sum
S
. A divergent series may still have a well-defined Cesàro sum. This Demonstration considers the series
∞
∑
k=0
sin(k)
, which is classically divergent but has the Cesàro sum
1
2
cot
1
2
.