Create a triangular matrix

Hello,

I have the following issue. I have a matrix A with dimensions 3x500 and I want to calculate the matrix B which is triangular of A. Below is the code I wrote:

% A: 3X500
B=zeros(length(A));
for i=1:length(B)
    for j=1:length(B)
        B(i,j)=exp(-(A(:,i)-A(:,j).^2)/5);
    end
end

The following error occurs:

Unable to perform assignment because the size of the left side is 1-by-1 and the size of the right side is

3-by-1.

How is this problem solved? Your help is important.

Answer 1

[Image Analyst]

You're subtracting the ith and jth column, which gives a whole column (3 values). Then you're trying to stuff those 3 values into a single location at B(i,j). You can't stuff 3 numbers into a position meant for one number. Not really sure what you want to do so not sure how to fix it.

For triangular matrices, see the functions tril() and triu().