As far as I know there is no deep reason, but it's traditional in the signal processing community, where a filter is a function that modifies a signal. https:/

As far as I know there is no deep reason, but it's traditional in the signal processing community, where a filter is a function that modifies a signal. https://en.wikipedia.org/wiki/Filter_(signal_processing) https://en.wikipedia.org/wiki/Filter_(signal_processing) Kalman trained as an electrical engineer (MIT and Columbia) so that's the lingo he was used to. There's a brief note in his Wikipedia page about having trouble publishing the technique at first. I'd like to hear the story. https://en.wikipedia.org/wiki/Rudolf_E._Kálmán https://en.wikipedia.org/wiki/Rudolf_E._Kálmán