how to access elements in a 2D array?

Question

I am new to python and I would like to understand how one goes about manipulating the elements of an array. If I have for example:

a= ( a11 a12 a13 )  and b          


        

Answer 1

a[1][1] does work as expected. Do you mean a11 as the first element of the first row? Cause that would be a[0][0].