MATLAB: Why the error is coming

Question

Trying to execute this code but it shows error "Subscript indices must either be real positive integers or logicals."

[M,N]=size(x); y=zeros(1,N); for l=1:N sum1=sum(x(:,l).*log(x(:,l))); sum1=-1*sum1; y(1,l)=sum1; end

Answer 1

who is x?

That message is the result of trying to access an non-existent element of the array, such as x(0).

Make sure x has the right size.

By the way, your for-loop code

x= rand(3,4); % sample data
[M,N]=size(x); 
y=zeros(1,N); 
for l=1:N
    sum1=sum(x(:,l).*log(x(:,l)));
    sum1=-1*sum1; 
    y(1,l)=sum1; 
end

Is the same that this, in a single line:

for l=1:N
    y(l) = -( sum(x(:,l).*log(x(:,l))) );
end