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How to evaluate sigma (summation) expression using meshgrid() and sum()?

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Yuval
Yuval 2013-3-27
I would like to evaluate the following expression using functions meshgrid, sum and dot operations: y = Ʃ(n=1 to N) xn*[cos(x2 + n2)/xn], where x is the vector of four equally spaced values from 1 to 2, N=10.
I wish to verify whether this is how it should be done:
n = 1:10;
x = linspace(1,2,4);
[X,N] = meshgrid(x,n);
y1 = (X.^N).*((cos(X.^2 + N.^2))./(X.*N));
y = sum(y1);
  2 个评论
Chaitanya Chitale
Chaitanya Chitale 2013-3-27
Yuval,
Could you confirm that the equation is: y = Ʃ(n=1 to N) xn*[cos(xn^2 + n^2)/xn]
Yuval
Yuval 2013-3-27
I am terribly sorry, the expression should have been: Ʃ(n=1 to N) [(x^n)*(cos(x^2 + n^2)/xn)]

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回答（1 个）

Image Analyst
Image Analyst 2013-3-27
"the expression should have been: Ʃ(n=1 to N) [(x^n)*(cos(x^2 + n^2)/xn)]"
well I would think that xn is the nth element of x and so should be just X. So the equation would be
y1 = (X.^N) .* cos(X.^2 + N.^2) ./ X;
Final Code
clc;
clearvars;
n = 1:10
x = linspace(1,2,4)
[X,N] = meshgrid(x,n)
y1 = (X.^N) .* cos(X.^2 + N.^2) ./ X
  1 个评论
Yuval
Yuval 2013-3-27
Typing xn, I took it for granted x*n was understood. Pardon me for that. Would you now please care to evaluate my original code (my first post)?

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