hw3_solutions - [L11, U11] = hw3lu (A11) ; % triangular...

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Computer Problems Additional function [L,U] = hw3lu (A) %HW3LU: [L,U] = hw3lu (A) computes the LU factorization of A. % L is computed one row at a time; U is computed one column at a time. [m n] = size (A) ; if (m ~= n) error ( 'A must be square' ) ; end if (n == 1) L = 1 ; U = A ; else % define A11, A12, A21, and A22: A11 = A (1:n-1, 1:n-1) ; A21 = A (n,1:n-1) ; A12 = A (1:n-1,n) ; A22 = A (n,n) ; % compute the LU factorization of A11
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Unformatted text preview: [L11, U11] = hw3lu (A11) ; % triangular solve for L21 (solve L21 * U11 = A21 for L21): L21 = A21 / U11 ; % triangular solve for U12 (solve L11 * U12 = A12 for U12): U12 = L11 \ A12 ; % Let L22 = 1 L22 = 1 ; % compute U22 by solving L21*U12 + L22*U22 = A22 for U22: U22 = A22 - L21*U12 ; % glue the results together L = [L11 zeros(n-1,1) ; L21 L22] ; U = [U11 U12 ; zeros(1,n-1) U22] ; end...
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hw3_solutions - [L11, U11] = hw3lu (A11) ; % triangular...

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