MATLAB: How to increase the columns of an NxM matrix to become NxN? (N>M) Not using reshape.

Question

Hi all,

I was hoping somebody could help me with this. Essentially, I have a 50×10 matrix and I want the matrix to be 50×50. I am trying to insert a couple of columns in between each column that I already have and then I want to make sure the values that are inserted have a linear trend between them. Here is an example of what I am trying to say:

A = [0  4 5; 
     0  5 1; 
     10 8 1; 
     2  4 6; 
     1 2 3] (5x3)

and I want the new matrix to be:

Anew = [0 2   4 4.5 5; 
        0 2.5 5 3   1; 
       10 9   8 4.5 1; 
        2 3   4 5   6; 
        1 1.5 2 2.5 3] (5x5)

Doing this by hand is easy for an example this small, but is there a way to do this via computations, or a function? I need to be able to do it for much larger matrices.

I hope my question is clear. Thanks in advance.

Answer 1

This works:

vi = linspace(1, 3, 5);                     % Interpolation Vector
for k1 = 1:size(A,1)    
    Anew(k1,:) = interp1([1:3], A(k1,:), vi, 'linear');
end