How To Calculate Double Summation In Matlb

Hi,

Can anyone help me in performing double summation of matrix elements using Matlab of the following equation:

Xc=[Sum(i=1 to 10)Sum(j=1 to 10){I(i,j)-I(m)}*H(i,j)*x]/[Sum(i=1 to 10)Sum(j=1 to 10){I(i,j)-I(m)}*H(i,j)]

Yc=[Sum(i=1 to 10)Sum(j=1 to 10){I(i,j)-I(m)}*H(i,j)*y]/[Sum(i=1 to 10)Sum(j=1 to 10){I(i,j)-I(m)}*H(i,j)].

Where: Sum represents summation,

I(i,j): Consider a 10x10 random matrix,

I(m): Middle element of the matrix I(i,j),

x & y: Co-ordinate of the matrix I(i,j),

H(i,j): H(i,j)=1; if I(i,j)>=I(m) 0; if I(i,j)<I(m).

Thanking You!

Answer 1

[Dishant Arora]

first thing is, how would you define a middle element in a 10*10 array.

Sum(i=1 to 10)Sum(j=1 to 10){I(i,j)-I(m)}*H(i,j)}

Btw, look at the above statement carefully, what you are doing is nothing but multiplying corresponding elements of 2 matrices and then summing up all the elements.you can accomplish this by:

mat=(I-I(m)).*H.*x;
summation=sum(mat(:));

[Dishant Arora]

H=zeros(size(I));
H(I>=I(m))=1;

gives you H, you need not to use if else statement. it's a powerful feature of matlab called logical indexing. http://blogs.mathworks.com/steve/2008/01/28/logical-indexing/ check out this blog.

[Image Analyst]

Yeah, that's what I asked him in his duplicate: http://www.mathworks.com/matlabcentral/answers/47267-how-to-execute-if-else-statement What does middle element mean?