error in this code on adaptive transmit power control in mitigating attenuation

function [K,L,T]=getfod(G,method) K=dcgain(G); if nargin==1 [Kc,Pm,wc,wcp]=margin(G); ikey=0; L=1.6*pi/(3*wc); T=0.5*Kc*K*L; if finite(Kc), x0=[L;T]; while ikey==0, u=wc*x0(1); v=wc*x0(2); FF=[K*Kc*(cos(u)-v*sin(u))+1+v^2; sin(u)+v*cos(u)]; J=[-K*Kc*wc*sin(u)-K*Kc*wc*v*cos(u), -K*Kc*wc*sin(u)+2*wc*v; wc*cos(u)-wc*v*sin(u), wc*cos(u)]; x1=x0-inv(J)*FF; if norm(x1-x0)<1e-8, ikey=1; else, x0=x1; end, end L=x0(1); T=x0(2); end elseif nargin==2 & method==1 [n1,d1]=tfderv(G.num{1},G.den{1}); [n2,d2]=tfderv(n1,d1); K1=dcgain(n1,d1); K2=dcgain(n2,d2); Tar=-K1/K; T=sqrt(K2/K-Tar^2); L=Tar-T; end