Cumulative sum of a number to create an array

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Isabelle Bester 2019-9-24

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https://ww2.mathworks.cn/matlabcentral/answers/481945-cumulative-sum-of-a-number-to-create-an-array

编辑： John D'Errico 2019-9-24

Hello!

I have a number (1182.225) and I am trying to create an array from this number that goes as follows:

Array = [1182.225, 1182.225*2, 1182.225*3, ..... 1182.225*24]

So that the array contains the number multiplied by 1 through 24 and each product is placed into the array. How can I write this in order to not type each multiplication manually?

Thanks for any feedback!

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Adam Danz 2019-9-24

Matt J's answer does what you're describing but note that it's not a cumulative sum (as mentioned in your question title).

John D'Errico 2019-9-24

编辑：John D'Errico 2019-9-24

在 MATLAB Online 中打开

Why does this feel somehow too silly to post as an answer to me?

1182.225*cumsum(ones(1,24))

Like using a Mack truck, to carry a pea to Boston. Well, not quite as bad.

Ok, perhaps this?

cumsum(1182.225)*(1:24)

Ok, I'm getting the hang of it now.

cumsum(1182.225)*diff((1:25).^2 - (1:25))/2

That seems to be closer to my target. :)

Hmm. Lets see, the roots of a one of the Chebyshef family of polynomials are equally spaced. I could construct the proper member, in symbolic form, then use solve to compute the roots. Or, I could construct a 24x24 matrix, with the property that one of the eigenvectors has the right shape. Easy enough. Then eig will do the work for me.

Nope. I like Matt's answer myself. Stick with that. :)

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