% determination of weighting function for multiplicative uncertainty model WT(s) s = tf('s'); wt1 = 2*pi*5; wt2 = 2*pi*2000; wt0 = 0.12; WT = wt0*(s+wt1)/wt1*wt2/(s+wt2); % notch filter zeta_1 = 0.5; zeta_2 = 0.1; wn = 2*pi*14; Fnotch = (s^2 + 2*zeta_1*wn*s + wn^2)/(s^2 + 2*zeta_2*wn*s + wn^2); WT = WT*Fnotch; WT_g = frd(WT, w); % multiplicative uncertainty delta1_g = (P1_g - P0_g)/P0_g; figure(3); clf; bodemag(WT_g, 'r-', delta1_g, 'b.'); legend('WT', 'multiplicative uncertainty', 'Location', 'NorthWest'); title('');