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function [n,nc,u,sl]=st_ility(sl,tol)
//stabilizability test
// Copyright INRIA
[lhs,rhs]=argn(0)
[a,b,c,d,x0,dom]=sl(2:7);
if dom==[] then
dom='c';warning('st_ility: time domain not given => sl assumed continuous!');
end
typ='c';if dom<>'c' then typ='d',end
[na,na]=size(a);[nw,nb]=size(b);
// controllable part
if rhs==1 then
if [a,b]~=[] then reltol=1.d-10*norm([a,b],1);else reltol=0;end
[a,b,u,n]=contr(a,b,[reltol,1.d-10])
else [a,b,u,n]=contr(a,b,tol)
end;
n=sum(n);nc=n;
if lhs==4 then c=c*u;x0=u'*x0;end
if n<>na then
//order evals uncont. part
nn=n+1:na
[v,n1]=schur(a(nn,nn),part(typ,1))
n=n+n1
//new realization
if lhs>2 then
u(:,nn)=u(:,nn)*v
if lhs==4 then
a(:,nn)=a(:,nn)*v;a(nn,nn)=v'*a(nn,nn)
b(nn,:)=v'*b(nn,:)
c(:,nn)=c(:,nn)*v
x0(nn)=v'*x0(nn)
end;
end;
end;
//
if lhs==4 then sl=syslin(dom,a,b,c,d,x0),end
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