If "V" and "W" are finite-dimensional and bases have been chosen, then "T" can be described by a matrix "M", and the kernel can be computed by solving the homogeneous system of linear equations . In this case, the kernel of "T" may be identified to the kernel of the matrix "M", also called "null space" of "M". The dimension of the null space, called the nullity of "M", is given by the number of columns of "M" minus the rank of "M", as a consequence of the rank–nullity theorem.