# Getting the summation of a series

6 views (last 30 days)
kalana agampodi on 26 Sep 2022
Commented: Torsten on 27 Sep 2022
Hi,
I am trying to get the sum from the given equation below.
My h values and h and ah variables are shown
h=[ 1 3 5 7 9 11 13 15]
ah = [35.8577 -6.2962 -1.2855 3.9251 -3.8197 2.2690 -0.4077 -0.9397 ]
alpha = linspace(0, 2* pi, 15)
N(alpha) =  I have written the code below, however when I plot the summation vs alpha I do not get the correct shape of the graph. The graph supposed to look like below Thank you
##### 2 CommentsShowHide 1 older comment
kalana agampodi on 26 Sep 2022
Hi,
the values of h has to be the values of h that is in the vector.
For an example when,
n=1, h=1
n=2, h=3
n=3, h=5
And it is same for the ah values
n=1, ah = 35.8577
n=2, ah = -6.2962
I have attach the photo of the equation.

Torsten on 26 Sep 2022
h=[ 1 3 5 7 9 11 13 15] ;
ah = [35.8577 -6.2962 -1.2855 3.9251 -3.8197 2.2690 -0.4077 -0.9397 ];
alpha = linspace(0,2*pi,15).';
N = sum(ah.*cos(h.*alpha),2);
plot(alpha,N) ##### 2 CommentsShowHide 1 older comment
Torsten on 27 Sep 2022
The indices for alpha and the (h,ah)-pairs must be different in your code. You used i for both of them.
Here is a code with a usual nested for-loop:
h=[ 1 3 5 7 9 11 13 15] ;
ah = [35.8577 -6.2962 -1.2855 3.9251 -3.8197 2.2690 -0.4077 -0.9397 ];
alpha = linspace(0,2*pi,15);
N = zeros(size(alpha));
for j = 1:length(alpha)
for i=1:length(h)
N(j) = N(j) + ah(i)*cos(h(i)*alpha(j));
end
end
plot(alpha,N) ### Categories

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