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function [L,U,P] = lu_rightpr (A)
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%LU_RIGHTPR recursive right-looking LU, with partial pivoting.
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% [L,U,P] = lu_rightpr (A)
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% Copyright 2006-2007, Timothy A. Davis.
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% http://www.cise.ufl.edu/research/sparse
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[x,i] = max (abs (A (1:n,1))) ; % partial pivoting
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P1 ([1 i],:) = P1 ([i 1], :) ;
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u11 = A (1,1) ; % (6.10)
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u12 = A (1,2:n) ; % (6.11)
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l21 = A (2:n,1) / u11 ; % (6.12)
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[L22,U22,P2] = lu_rightpr (A (2:n,2:n) - l21*u12) ; % (6.9) or (6.13)
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L = [ 1 o ; P2*l21 L22 ] ; % (6.14)
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U = [ u11 u12 ; o' U22 ] ;
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P = [ 1 o ; o' P2] * P1 ;