Maxima Function
nullspace (M)
If M is a matrix, return span (v_1, ..., v_n), where the set {v_1, ..., v_n} is a basis for the nullspace of M. The span of the empty set is {0}. Thus, when the nullspace has only one member, return span ().
span (v_1, ..., v_n)
{v_1, ..., v_n}
{0}
span ()