
676 Optimal Estimation of Dynamic Systems
if a
kk
= 0
a
jk
← a
kj
/a
kk
, j = k + 1,...,n
a
jj
← a
jj
−a
jk
a
kj
, j = k + 1,...,n
end if
next k
where ← denotes replacement and ↔ denotes “interchange the value assigned to.”
The matrix U is given by the upper triangular part (including the diagonal elements)
of the overwritten A matrix, and the matrix L is given by the lower triangular part
(replacing the diagonal elements with ones) of the overwritten A matrix. More details
on Gaussian elimination can be found in Ref. [4].
LU and Cholesky Decompositions
The LU decomposition factors an n ×n matrix A into a product of a lower trian-
gular matrix L and an upper triangular ...