# freqs

Compute analog filter frequency response values.

## Syntax

h = freqs(b,a,w)

[h,w] = freqs(...)

## Inputs

`b`- The numerator polynomial coefficients of the filter.
`a`- The denominator polynomial coefficients of the filter.
`w`- The frequencies (in radians/sec) at which the response is computed.

## Outputs

- h
- The frequency response values.
`w`- The frequencies (in radians/sec) at which the response is computed.

## Example

Verify the cutoff frequency of a fourth order Butterworth low pass analog filter with a 300
radians/sec cutoff
frequency.

```
b = [0.0, 0.0, 0.0, 0.0, 8.10000e+09];
a = [1.0, 7.83938e+02, 3.07279e+05, 7.05544e+07, 8.10000e+09];
h = freqs(b,a,300);
abs(h)
```

`ans = 0.70711`