Fig. 4: ρ4 approximation.

Approximation of ρ4 with error given by \(\Vert{\rho }_{4}-{\rho }_{4}^{{\prime} }{\Vert}_{1}=\Vert{\Delta }_{4}{\Vert}_{1}\).

Approximation of ρ4 with error given by \(\Vert{\rho }_{4}-{\rho }_{4}^{{\prime} }{\Vert}_{1}=\Vert{\Delta }_{4}{\Vert}_{1}\).