### More General Real FIR Filters

So far we have looked at the design of linear phase filters. In this
case,
,
and
are all real. In some
applications, we need to specify both the *magnitude* and
*phase* of the frequency response. Examples include

- minimum phase filters [263],
- inverse filters (``deconvolution''),
- fractional delay filters [266],
- interpolation polyphase subfilters (Chapter 11)

*complex*desired frequency-response samples ( complex), and the matrix remains a more general Fourier transform matrix that cannot be reduced to a matrix of cosines.

**Next Section:**

Nonlinear-Phase FIR Filter Design

**Previous Section:**

Chebyshev FIR Design via Linear Programming