Editing Wavelet (section)

=== Scaling function ===
Wavelets are defined by the wavelet function ψ(''t'') (i.e. the mother wavelet) and scaling function φ(''t'') (also called father wavelet) in the time domain.

The wavelet function is in effect a band-pass filter and scaling that for each level halves its bandwidth. This creates the problem that in order to cover the entire spectrum, an infinite number of levels would be required. The scaling function filters the lowest level of the transform and ensures all the spectrum is covered. See<ref>{{cite web|url=http://www.polyvalens.com/blog/?page_id=15#7.+The+scaling+function+%5B7%5D|title=A Really Friendly Guide To Wavelets – PolyValens|website=www.polyvalens.com}}</ref> for a detailed explanation.

For a wavelet with compact support, φ(''t'') can be considered finite in length and is equivalent to the scaling filter ''g''.

Meyer wavelets can be defined by scaling functions