Sum of matrix with variable dimension

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Favier 2016-10-29

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https://ww2.mathworks.cn/matlabcentral/answers/309747-sum-of-matrix-with-variable-dimension

评论： Favier 2016-10-30

Hello, I have two matrices produced by meshgrid and a simple scalar:

r = 1:10;
N = 1:10;
[r,N] = meshgrid(r,N);
N0 = 4;

I want, for each value of N, to get the sum from N0 to N of r^n. However this Matlab commands is not working :

sum(r.^(N0:N));

For example for r(5,5) = 5 and N(5,5) = 5, the result would be 5^4 + 5^5 = 3750. What I want is to get the matrix resultant of this operation over each row and column of r and N.

Thank you for your help!

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Image Analyst 2016-10-29

Why is the N value raised to the 5th power while the r value is raised to the 4th power? What does it mean to have an exponent that is a vector, like [4,5]?

Favier 2016-10-29

Thank you for your interest. Sorry I should have detailed my example a bit more. When I write 5^4 + 5^5 = 3750, it should be read as r(5,5)^N0 + r(5,5)^N(5,5) = 3750.

If N0 = 4 and N(5,5) = 7, then I want to calculate r(5,5)^N0 + r(5,5)^(N0+1) + r(5,5)^(N0+2) + r(5,5)^(N(5,5))

The exponent is a vector to simplify the representation. What I want is to calculate the sum of r^n with n from N0 to N for ALL my r and ALL my N. The larger the N, the more terms I have in the sum. That is the purpose of the vector exponent.

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