Note: This page has been translated by MathWorks. Please click here

To view all translated materals including this page, select Japan from the country navigator on the bottom of this page.

To view all translated materals including this page, select Japan from the country navigator on the bottom of this page.

Impulse response length

`len = impzlength(b,a)`

`len = impzlength(sos)`

`len = impzlength(d)`

`len = impzlength(hd)`

`len = impzlength(___,tol)`

returns
the impulse response length for the causal discrete-time filter with
the rational system function specified by the numerator, `len`

= impzlength(`b`

,`a`

)`b`

,
and denominator, `a`

, polynomials in * z^{–1}*.
For stable IIR filters,

`len`

is the effective
impulse response sequence length. Terms in the IIR filter's
impulse response after the `len`

-th term are essentially
zero.

returns
the effective impulse response length for the IIR filter specified
by the second order sections matrix, `len`

= impzlength(`sos`

)`sos`

. `sos`

is
a * K*-by-6 matrix, where the number of sections,

`impzlength`

considers the input to be
the numerator vector, `b`

. Each row of `sos`

corresponds
to the coefficients of a second order (biquad) filter. The `sos`

matrix corresponds to ```
[bi(1)
bi(2) bi(3) ai(1) ai(2) ai(3)]
```

.

returns
the impulse response length for the digital filter, `len`

= impzlength(`d`

)`d`

.
Use `designfilt`

to generate `d`

based
on frequency-response specifications.

specifies
a tolerance for estimating the effective length of an IIR filter's
impulse response. By default, `len`

= impzlength(___,`tol`

)`tol`

is `5e-5`

.
Increasing the value of `tol`

estimates a shorter
effective length for an IIR filter's impulse response. Decreasing
the value of `tol`

produces a longer effective
length for an IIR filter's impulse response.

`designfilt`

| `digitalFilter`

| `impz`

| `zp2sos`

Was this topic helpful?