	function nf = NatFreq(F,Sys)
%	Natural Frequencies, Periods, Damping Ratios, and Real Roots
%	============================================================
%   July 5, 2023
%	==========================================================
%	Copyright 2023 by ROBERT F. STENGEL.  All rights reserved.

	nf	=	1;  %   Dummy
	Eigenvalue	=   esort(eig(F))
    
    for i = 1:length(Eigenvalue)
        if imag(Eigenvalue(i)) == 0
            Tau =   -1/real(Eigenvalue(i));
            disp(['Time constant = ',num2str(Tau),' s'])
        else
            wn      =   sqrt((real(Eigenvalue(i))^2 + (imag(Eigenvalue(i))^2)));
            zeta    =   -real(Eigenvalue(i))/wn;
            P       =   2*pi/wn;
            disp(['Natural frequency = ',num2str(wn),' rad/s',', Damping ratio = ',num2str(zeta)])
            disp(['Period = ',num2str(P),' s'])
        end
    end
    
    
