Introduction - If you have any usage issues, please Google them yourself
In almost all analyzes of the least mean-square (LMS)
finite impulse response (FIR) adaptive algorithm, it is assumed that
the length of the adaptive filter is equal to that of the unknown
system impulse response. However, in many practical situations,
a deficient length adaptive filter, whose length is less than that of
the unknown system, is employed, and analysis results for the sufficient
length LMS algorithm are not necessarily applicable to the
deficient length case.