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function [L,U] = lu_rightr (A)
%LU_RIGHTR recursive right-looking LU.
% Example:
% [L,U] = lu_rightr (A)
% See also: cs_demo
% CXSparse, Copyright (c) 2006-2022, Timothy A. Davis. All Rights Reserved.
% SPDX-License-Identifier: LGPL-2.1+
n = size (A,1) ;
if (n == 1)
L = 1 ;
U = A ;
else
u11 = A (1,1) ; % (6.4)
u12 = A (1,2:n) ; % (6.5)
l21 = A (2:n,1) / u11 ; % (6.6)
[L22,U22] = lu_rightr (A (2:n,2:n) - l21*u12) ; % (6.7)
L = [ 1 zeros(1,n-1) ; l21 L22 ] ;
U = [ u11 u12 ; zeros(n-1,1) U22 ] ;
end
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