function K0=ps14f_6242_2004(N)
% function K0=ps14f_6242_2004(N)
%
% gain margin estimation for Problem 1.4(f) in 6.242/2004
w=(1:N)'*50/N;                             % frequency samples
sqrts=((1+j)/sqrt(2))*sqrt(w);              % sqrt(s) samples
Gs=2./(sqrts.*(exp(sqrts)-exp(-sqrts)));    % G samples
ir=imag(Gs);                                
ir=ir(1:N-1).*ir(2:N);
y=min(real(Gs(ir<=0)));
K0=-1/y;
close(gcf)
subplot(2,1,1); plot(w,real(Gs),w,repmat(y,N,1)); grid
subplot(2,1,2); plot(w,imag(Gs)./max(0.1,abs(imag(Gs)))); grid