latcfilt
Lattice and lattice-ladder filter implementation
Syntax
[f,g] = latcfilt(k,x)
[f,g] = latcfilt(k,v,x)
[f,g] = latcfilt(k,1,x)
[f,g,zf] = latcfilt(...,'ic',zi)
[f,g,zf] = latcfilt(...,dim)
Description
When filtering data,
lattice coefficients can be used to represent
FIR filters
All-pole IIR filters
Allpass IIR filters
General IIR filters
[f,g] = latcfilt(k,x) filters x with
the FIR lattice coefficients in the vector k.
The forward lattice filter result is f and g is
the backward filter result. If , f corresponds
to the minimum-phase output, and g corresponds
to the maximum-phase output.
If k and x are vectors,
the result is a (signal) vector. Matrix arguments are permitted under
the following rules:
If
xis a matrix andkis a vector, each column ofxis processed through the lattice filter specified byk.If
xis a vector andkis a matrix, each column ofkis used to filterx, and a signal matrix is returned.If
xandkare both matrices with the same number of columns, then the ith column ofkis used to filter the ith column ofx. A signal matrix is returned.
[f,g] = latcfilt(k,v,x) filters x with
the IIR lattice coefficients k and ladder coefficients v.
Both k and v must be vectors,
while x can be a signal matrix.
[f,g] = latcfilt(k,1,x) filters x with
the IIR lattice specified by k, where k and x can
be vectors or matrices. f is the all-pole lattice
filter result and g is the allpass filter result.
[f,g,zf] = latcfilt(...,'ic',zi) accepts
a length-k vector zi specifying
the initial condition of the lattice states. Output zf is
a length-k vector specifying the final condition
of the lattice states.
[f,g,zf] = latcfilt(...,dim) filters x along
the dimension dim. To specify a dim value,
the FIR lattice coefficients k must be a vector
and you must specify all previous input parameters in order. Use the
empty vector [ ] for any parameters you do not want to specify. zf returns
the final conditions in columns, regardless of the shape of x.
Examples
FIR Lattice Filter
Generate a signal with 512 samples of white Gaussian noise.
x = randn(512,1);
Filter the data with an FIR lattice filter. Specify the reflection coefficients so that the lattice filter is equivalent to a 3rd-order moving average filter.
[f,g] = latcfilt([1/2 1],x);
Plot the maximum- and minimum-phase outputs of the lattice filter in separate plots
subplot(2,1,1) plot(f) title('Maximum-Phase Output') subplot(2,1,2) plot(g) title('Minimum-Phase Output')
