T-Squared | Native iOS client for Georgia Tech | iOS library

In most filters, you want the output magnitude to remain equal after filtering, not scaled up or down.

Mathematically this is generally properly done in the filter equation, but in discrete numbers this doesnt generally doesn't apply.

If you divide the filer by its sum, you make sure that for any input data p, the filter will always have a general scale factor of 1, as its normalized. For a p=ones(1:1000,1), if sum(h) is not 1, the result after filtering will be scaled, i.e. the values of p_filtered will not be 1.