Computing summation in matlab

2013 2 22
2 个回答
4 次查看（30 天）

0 个投票

I have a matrix let say A=ones(144,40);
and I want to compute the summation with lower limit is 1 and upper limit is dimension of A like 144*40=5760.
How can I compute it using symsum or sum other function?

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回答（2 个）

Wayne King
Wayne King 2013-2-22
编辑：Wayne King 2013-2-22

0 个投票

A = ones(144,40);
B = sum(A(:));
or
B = sum(sum(A));
Mark Whirdy
Mark Whirdy 2013-2-22
编辑：Mark Whirdy 2013-2-22

0 个投票

If Wayne is right and you're talking about limits to the summation, is it that you want to control these limits as parameters, or you simply want to always sum over every element (1:(size(A,1)*size(A,2))) of the matrix?
Wayne provides the latter solution, a solution to the former might be
limitSum = @(X,l_b,u_b)(sum(X(l_b:u_b))); % define amonymous function
A = ones(144,40);
limitSum(A,1,size(A,1)*size(A,2)); % apply function to A

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Wayne King
Wayne King 2013-2-22
I think the OP is just referring to the limits of the summation as in
\sum_{n=1}^{N} x[n]
Algorithms Analyst
Algorithms Analyst 2013-2-22
No...it mean when we compute summation this is a lower and upper limit
5760
like SUM(A).where is matrix of size 144x40.
1
Thanks...any help plz
Algorithms Analyst
Algorithms Analyst 2013-2-22
where A is matrix of size 144x40
Wayne King
Wayne King 2013-2-22
did you look at my answer? that sums all the elements in the matrix
Mark Whirdy
Mark Whirdy 2013-2-22
then its just a sum as Wayne said

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