>    M := 100;

M := 100

>    Sum( sin(n*x)/n , n=1..M);

Sum(sin(n*x)/n,n = 1 .. 100)

>    partial_sum := unapply(value(%),x):

>    plot(partial_sum, -6..3);

[Maple Plot]

>    (1/M)*Sum( Sum( sin(n*x)/n , n=1..N), N=1..M);

1/100*Sum(Sum(sin(n*x)/n,n = 1 .. N),N = 1 .. 100)

>    Cesaro_mean := unapply(value(%),x):

>    plot(Cesaro_mean, -6..3);

[Maple Plot]

>   

>   

>