this a function of LU Division in matlab
function [L,U]=lu_factor(A) % A is the matrix
[n,m]=size(A);
L=eye(A);
U=A;
for j=1:n
for i=j+1:n
L(i,j) = U(i,j) / U(j,j);
U(i,j) = U(i,
- L(i,j)*U(j,
;
end
end
% doolittle methods
function[L,U] = doolittle(a)
[n,m]=size(A);
U = zeros(n,n);
L = eye(n);
for k=1:n
U(1,k) = A(1,k);
L(k,1) = A(k,1)/U(1,1);
end
for k=2:n
U(k,k) = A(k,k)-L(k,1:k-1)*U(1:k-1,k);
for j=k+1:n
U(k,j)=A(k,j)-L(k,1:k-1)*U(1:k-1,j);
L(j,k)=(A(j,k)-L(j,1:k-1)*U(1:k-1,k))/U(k,k);
end
end