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function [A,B,Q,Z] = qzdiv(stake,A,B,Q,Z)
%function [A,B,Q,Z] = qzdiv(stake,A,B,Q,Z)
%
% Takes U.T. matrices A, B, orthonormal matrices Q,Z, rearranges them
% so that all cases of abs(B(i,i)/A(i,i))>stake are in lower right
% corner, while preserving U.T. and orthonormal properties and Q'AZ' and
% Q'BZ'.
% Original file downloaded from:
% http://sims.princeton.edu/yftp/gensys/mfiles/qzdiv.m
% Copyright (C) 1993-2007 Christopher Sims
% Copyright (C) 2008-2017 Dynare Team
%
% This file is part of Dynare.
%
% Dynare is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
%
% Dynare is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
% GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with Dynare. If not, see <http://www.gnu.org/licenses/>.
[n, jnk] = size(A);
root = abs([diag(A) diag(B)]);
root(:,1) = root(:,1)-(root(:,1)<1.e-13).*(root(:,1)+root(:,2));
root(:,2) = root(:,2)./root(:,1);
for i = n:-1:1
m=0;
for j=i:-1:1
if (root(j,2) > stake || root(j,2) < -.1)
m=j;
break
end
end
if (m==0)
return
end
for k=m:1:i-1
[A, B, Q, Z] = qzswitch(k,A,B,Q,Z);
tmp = root(k,2);
root(k,2) = root(k+1,2);
root(k+1,2) = tmp;
end
end
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