%  Example 7.7.  Computing the  plant noise spectral density from the 
%    output spectral density.
clear
%  Define the plant model.
A=-0.1; Bw=3; Bu=3; Cm=1;
%  Define the measurement variance (assuming no measurement noise).
VARm=0.4;
%  Compute the measurement variance assuming unity plant noise spectral
%    density.
VARm1=lyap(A,Bw'*1*Bw);
%  Compute the true plant noise spectral density.
Sw=VARm/VARm1
