An algorithm for removing noise from numeric sequences. LULU smoothing can be used to flatten out sudden peaks or valleys. The LULU algorithm can apply one of two smoothing filters repeatedly to the entire sequence. One removes sudden upwards jumps and is called the "lower" or "L" filter. The other available operation removes sudden downward plunges and is called "upper" or "U" filter. Here "LULU" refers to the default sequence of filters.