Dimension mismatch error in matlab

This is my code.

    for r=1:4
    vec=[10:20] +r;
    mat(r,:)=vec
    end

I want to get separate vector as output after every iteration.but I am getting dimension mismatch error.Can anyone help please?

[Ameer Hamza]

The code you posted works perfectly fine. The output at the end is

mat =
  11    12    13    14    15    16    17    18    19    20    21
  12    13    14    15    16    17    18    19    20    21    22
  13    14    15    16    17    18    19    20    21    22    23
  14    15    16    17    18    19    20    21    22    23    24

Make sure that mat is not already present in the workspace. If present try running

clear mat

[Adam]

Ideally you should presize mat before the for loop.

[Tasnim Tamanna]

Thanks a lot..it works now.