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reset

System object: dsp.IIRFilter
Package: dsp

Reset internal states of IIR filter

Syntax

reset(iir)

Description

reset(iir) resets the filter states of the IIR filter object, iir, to their initial values of 0. The initial filter state values correspond to the initial conditions for the difference equation defining the filter. After the step method applies the IIR filter object to nonzero input data, the states may be nonzero. Invoking the step method again without first invoking thereset method may produce different outputs for an identical input.

Reset an IIR Filter

Note: This example runs only in R2016b or later. If you are using an earlier release, replace each call to the function with the equivalent step syntax. For example, myObject(x) becomes step(myObject,x).

iir = dsp.IIRFilter;
[b,a] = ellip(20, 0.5, 80, 0.25);
iir.Numerator = b;
iir.Denominator = a;
n = 0:100;
x = cos(0.2*pi*n)+sin(0.8*pi*n);
y = iir(x);

Filter states are nonzero. Call the IIR filter without resetting states.

y1 = iir(x);
isequal(y,y1)
ans =

  logical

   0

Now reset filter states to 0.

reset(iir)

Call the IIR filter again.

y2 = iir(x);
isequal(y,y2)
ans =

  logical

   1

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