What is the complexity of matrix addition?

Question

I have found some mentions in another question of matrix addition being a quadratic operation. But I think it is linear.

If I double the size of a matrix, I need to calc

Answer 1

think of the general case implementation:

for 1 : n
 for 1 : m
   c[i][j] = a[i][j] + b[i][j]

if we take the simple square matrix, that is n x n additions