
# The ; denotes we are going back to a new row.
A = [[1, 2, 3], [4, 5, 6], [7, 8, 9], [10, 11, 12]]

# Initialize a vector
v = [[1], [2], [3]]

# Get the dimension of the matrix A where m = rows and n = columns
# [m,n] = size(A)

# You could also store it this way
# dim_A = size(A)

# Get the dimension of the vector v
# dim_v = size(v)

# Now let's index into the 2nd row 3rd column of matrix A
# A_23 = A(2,3)