matrix element summation algorithm

Hi!

I have a matrix A [ 1 2 3; 3 1 2; 1 2 1]. I want to get the sum of A(1,1)+A(2,1) + A(3,3), which will be the result of a general algorithm which will follow the following logic: since A(1,1)=1, the second term in the sum will be the second row of A, and column 1 since A(1,1)=1. Therefore the second term in the sum will be A(2,1). Then, since A(2,1)=3, the third term in the sum will be the third row of A, and it's 3rd column, since A(2,1)=3 (in other words, the A(.,.) value determines the column from which the term will be taken, and we move successively down the matrices rows).

I hope I managed to explain this!

Thanks,

Filippos

[Image Analyst]

Sounds like homework. If it is, please read this link. If it's not, what is the question? There is no question there, just an announcement of what you're going to do, presumably with a simple for loop.

Answer 1

[madhan ravi]

Hi try this :

sum(diag(A))

[madhan ravi]

if it worked accept the answer