'Assignment has more non-singleton rhs dimensions than non-singleton subscripts'. Can you guys help me fixing this error?

I have a 3D matrix called a. Apit= 3x4x20. And i want a matrix U(20,1) that gives me the sum of each 20 matrix. And i was doing this way: (i is 20)

for i = 1:t

      U(i,1) = sum(Apit(:,:,i));

end

And when i run, it appears that error. Can you help me?

Answer 1

[Rik]

The output of sum is a vector, as the input is a 2D matrix. To calculate the sum over all rows and cols, you can use the code below:

U=squeeze(sum(sum(Apit,1),2));

[Pedro Vicente]

It worked!! Thanks a lot.