Frequency response of filter
[h,w]
= freqz(sysobj)
[h,w]
= freqz(sysobj,n)
[h,w] =
freqz(sysobj,Name,Value)
freqz(sysobj)
[
returns the complex
frequency response h
,w
]
= freqz(sysobj
)h
of the filter System
object™, sysobj
.
The vector w
contains the frequencies (in radians)
at which the function evaluates the frequency response. The frequency
response is evaluated at 8192 points equally spaced around the upper
half of the unit circle.
[
returns
the complex frequency response of the filter System
object and
the corresponding frequencies at h
,w
]
= freqz(sysobj
,n
)n
points equally
spaced around the upper half of the unit circle.
freqz
uses the transfer function associated
with the filter to calculate the frequency response of the filter
with the current coefficient values.
[
returns
a frequency response with additional options specified by one or more h
,w
] =
freqz(sysobj
,Name,Value
)Name,Value
pair
arguments.
freqz(
uses sysobj
)fvtool
to
plot the magnitude and unwrapped phase of the frequency response of
the filter System
object sysobj
.
For more information about optional input arguments for freqz
,
refer to freqz
in Signal
Processing Toolbox™ documentation.

Complex 

Frequency vector of length 
There are several ways of analyzing the frequency response of
filters. freqz
accounts for quantization effects
in the filter coefficients, but does not account for quantization
effects in filtering arithmetic. To account for the quantization effects
in filtering arithmetic, refer to function noisepsd
.
freqz
calculates the frequency response
for a filter from the filter transfer function Hq(z).
The complexvalued frequency response is calculated by evaluating Hq(e^{j}^{ω})
at discrete values of w specified by the syntax
you use. The integer input argument n
determines
the number of equallyspaced points around the upper half of the unit
circle at which freqz
evaluates the frequency
response. The frequency ranges from 0 to π radians per sample
when you do not supply a sampling frequency as an input argument.
When you supply the scalar sampling frequency fs
as
an input argument to freqz
, the frequency ranges
from 0 to fs
/2 Hz.