2-D frequency response

`[`

returns `H`

,`f1`

,`f2`

] = freqz2(`h`

)`H`

, the `64`

-by-`64`

frequency response of `h`

, and the frequency vectors
`f1`

(of length `64`

) and
`f2`

(of length `64`

). `h`

is
a two-dimensional FIR filter, in the form of a computational molecule.

`freqz2`

returns `f1`

and `f2`

as normalized frequencies in the range -1.0 to 1.0, where 1.0 corresponds to half
the sampling frequency, or π radians.

`[`

returns the frequency response for the FIR filter `H`

,`f1`

,`f2`

] = freqz2(`h`

,`f1, f2`

)`h`

at frequency
values in `f1`

and `f2`

. These frequency values
must be in the range -1.0 to 1.0, where 1.0 corresponds to half the sampling
frequency, or π radians. You can also specify `[f1 f2]`

as two
separate arguments, `f1, f2`

.

`[___] = freqz2(h,___,`

uses `[dx dy]`

)`[dx dy]`

to override the intersample spacing in
`h`

. You can also specify a scalar to specify the same spacing
in both the *x* and *y* dimensions.

`freqz2(___)`

produces a mesh plot of the
two-dimensional magnitude frequency response when no output arguments are
specified.