Another measure is the manipulability. This measures the ability of the manipulator to move uniformly in all directions. At the singular points, the manipulator loses one or more degrees of freedom. In other words, some tasks cannot be performed at or near singular points. A quantitative measure for the manipulability of a robot is defined as:
where 
is the Jacobian matrix which is the first derivative of the
position vector of the end-effector.
By maximizing this measure for the length of each link, the manipulator will
have a maximally large well-conditioned workspace.