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Frequency response of filter

```
[h,w]
= freqz(sysobj)
```

```
[h,w]
= freqz(sysobj,n)
```

```
[h,w]
= freqz(sysobj,'Arithmetic',arithType)
```

`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/sample) 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.

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 complex-valued
frequency response is calculated by evaluating
*Hq*(*e ^{j}^{ω}*)
at discrete values of

`n`

determines the number of equally-spaced 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.