dfilt.df1t
Discrete-time, direct-form I transposed filter
Syntax
Hd = dfilt.df1t(b,a)
Hd = dfilt.df1t
Description
Hd = dfilt.df1t(b,a)
returns a
discrete-time, direct-form I transposed filter, Hd
, with numerator
coefficients b
and denominator coefficients a
. The
filter states for this object are stored in a filtstates
object.
Hd = dfilt.df1t
returns a default,
discrete-time, direct-form I transposed 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.
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 of states is:
Alternatively, you can access the states in the filtstates object:
b = [0.05 0.9 0.05]; Hd = dfilt.df1t(b,1); Hd.States % Returns % Numerator: [2x1 double] % Denominator: [0x1 double] Hd.States.Numerator(1)=1; %Set zb(1) equal to 1.
Examples
Create a direct-form I transposed discrete-time filter with coefficients from a fourth-order lowpass Butterworth design:
[b,a] = butter(4,.5); Hd = dfilt.df1t(b,a)
Version History
Introduced before R2006a