From: Iterative unbiased FIR state estimation: a review of algorithms
Stage
Given:
K, N, m=n−N+1⩾0, s=m+K−1,
m+K⩽l⩽n.
Set:
x ̂ s by (69) and G s by (70).
Update:
G l = [ H l T H l + ( F l G l − 1 F l T ) − 1 ] − 1 ,
x ̂ l = F l x ̂ l − 1 + G l H l T ( z l − H l F l x ̂ l − 1 ).
Instruction:
Use the estimate when l=n.