Getting the summation of a series

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kalana agampodi 2022-9-26

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1812500-getting-the-summation-of-a-series

评论： Torsten 2022-9-27

采纳的回答： Torsten

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.

Can you please help me with getting the summation and plotting it against the alpha ?

The graph supposed to look like below

Thank you

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Dyuman Joshi 2022-9-26

Note that the formulae in the image specifies that h is 1,2,3,4,....13,14,15 and not 1,3,5,...13,15.

And which sum do you want to plot? Regular sum (which will be a single value) or cummulative sum? Or any other sum? If so, then please define the sum.

kalana agampodi 2022-9-26

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.

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Answer 1

Torsten 2022-9-26

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1812500-getting-the-summation-of-a-series#answer_1061110

在 MATLAB Online 中打开

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)

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kalana agampodi 2022-9-26

移动：Star Strider 2022-9-26

Thank you. I was thinking if I run through every element in the array using a for loop it will do the same thing. But apperently its matrix muliplication.

Thnaks