A Musical Time-Varying Filter Example
Note, however, that a gain 
may vary with time independently
of 
to yield a linear time-varying filter. In this case,
linearity may be demonstrated by verifying
![$\displaystyle g(n) \left[ \alpha \cdot x_1(n) + \beta \cdot x_2(n)\right]
= \alpha \cdot [g(n)\cdot x_1(n)] + \beta\cdot[g(n)\cdot x_2(n)]
$](http://www.dsprelated.com/josimages_new/filters/img495.png){kind=small}
. For example,
![$ g(n) = 1
+ \cos[2\pi (4)nT]$](http://www.dsprelated.com/josimages_new/filters/img497.png){kind=small}
would give a maximally deep tremolo with 4 swells
per second.
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Analysis of Nonlinear Filters
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Nonlinear Filter Example: Dynamic Range Compression
