ImprovedReducedSystem( K , M , SlaveDofs )

function [KR,MR,Ti] = ImprovedReducedSystem( K , M , SlaveDofs )
%
%  Improved Reduced System (IRS)
%  with this method, the reduced model tries to reproduce 
%  the natural freq.s of full model.
% 
% K , M : Full order stiffness & Mass Matrices
% SlaveDofs : Dofs to be deattached from system
% KR, MR : Reduced stiffness & Mass Matrices
% Ti : Transformation Matrix
%
%  Needs GuyanReduction.m file which is already published in Matlab
%  Central.
%
%  M.M.Altug Bicak @ 2006
%  Michigan Technological University

[KR,MR,T,Kss] = GuyanReduction( K , M , SlaveDofs) ;

Si = zeros(size(K));
Si(size(K)) = 1 ;
S = Si*inv(Kss) ;

Ti = T + S*M*T*inv(MR)*KR ;

 MR = Ti'*M*Ti;
 KR = Ti'*K*Ti;