A vector wL of length Lin the direction of a vector u = xi + yj + zk can determined by wL = Lun (multiplying a unit vector in the direction of u by L). The unit vector un in the direction of the vector u is given by un = xi + yj + zk/√x2 + y2 + z2. By writing MATLAB command, determine a vector of length 18 in the direction of the vector u = 7i - 4j - 11k.