dfilt.df1
Discrete-time, direct-form I filter
Syntax
Hd = dfilt.df1(b,a)
Hd = dfilt.df1
Description
Hd = dfilt.df1(b,a)
returns a
discrete-time, direct-form I filter, Hd
, with numerator coefficients
b
and denominator coefficients a
. The filter
states for this object are stored in a filtstates
object.
Hd = dfilt.df1
returns a default,
discrete-time, direct-form I filter, Hd
, with b
=1
and a
=1. This filter passes the input through to the output
unchanged.
Note
The leading coefficient of the denominator a(1)
cannot be 0.
Image of direct form one filter diagram
To display the filter states, use this code to access the
filtstates
object.
Hs = Hd.states % Where Hd is the dfilt.df1 object and double (Hs) % Hs is the filtstates object
The vector is
Examples
Create a direct-form I discrete-time filter with coefficients from a fourth-order lowpass Butterworth design
[b,a] = butter(4,.5); Hd = dfilt.df1(b,a)
Version History
Introduced before R2006a