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// Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
// Copyright (C) INRIA -
//
// This file must be used under the terms of the CeCILL.
// This source file is licensed as described in the file COPYING, which
// you should have received as part of this distribution. The terms
// are also available at
// http://www.cecill.info/licences/Licence_CeCILL_V2.1-en.txt
function [h,err]=time_id(n,u,y)
[lhs,rhs]=argn(0)
y=y(:)
npt=size(y,"*");
select type(u)
case 1 then
u=u(:)
case 10 then
select part(u,1)
case "i" then
u=eye(npt,1)
case "s" then
u=ones(npt,1)
else
error(msprintf(gettext("%s: Wrong value for input argument #%d: Must be in the set {%s}.\n"),"time_id",2,"""i"",""s"""))
end
else
error(msprintf(gettext("%s: Wrong value for input argument #%d: Must be in the set {%s}.\n"),"time_id",2,"""i"",""s"""))
end
if y(1)==0 then // strictly proper case
m(npt-1,2*n)=0;
for k=1:n,m(k:npt-1,[k k+n])=[-y(1:npt-k) u(1:npt-k)];end
coef=m\y(2:npt);
num=poly(coef(2*n:-1:n+1),"z","c");
den=poly([coef(n:-1:1);1],"z","c");
else
m(npt,2*n+2)=0;
for k=1:n+1,m(k:npt,[k k+n+1])=[-y(1:npt-k+1) u(1:npt-k+1)];end
coef=-m(:,2:$)\m(:,1)
num=poly(coef(2*n+1:-1:n+1),"z","c");
den=poly([coef(n:-1:1);1],"z","c");
end
h=syslin("d",num,den)
if lhs==2 then
err=norm(y-rtitr(num,den,u')',2)
end
endfunction
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