Filter Design Toolbox

Function Reference

Functions--By Category

With the Filter Design (FD) Toolbox, you can create, apply, and analyze quantized filters, quantizers, and quantized fast Fourier transforms (FFTs). This chapter contains brief descriptions of all FD Toolbox functions grouped by subject area, and continues with the detailed reference entries listed alphabetically. The following tables list the functions in the FD Toolbox, separated by quantization application--quantized filter, quantizer, or quantized FFT. In many instances, you can apply a function to more than one application; those functions are called overloaded functions and they appear in more than one table.

Quantized Filter Construction and Property Functions

Function	Description
get	Get properties of a quantized filter
isreal	Test if filter coefficients are real
num2bin	Convert a number to two's-complement binary string
num2hex	Convert a number to hexadecimal string
qfilt	Construct a quantized filter (Qfilt object)
qreport	Returns the listing of a quantize filter and its properties
reset	Reset the properties of a quantized filter to their initial values
set	Set properties of a quantized filter
setbits	Set the data format property values for a quantized filter

Quantized Filter Analysis Functions 

Function	Description
freqz	Compute the frequency response for a quantized filter
impz	Compute the impulse response for a quantized filter
isallpass	Test quantized filters to determine if they are allpass structures
isfir	Test quantized filters to see if they are FIR filters
islinphase	Test quantized filters to see if they are linear phase
ismaxphase	Test quantized filters to see if they are maximum phase filters
isminphase	Test quantized filters to see if they are minimum phase filters
isreal	Test qauntized filters for purely real coefficients
issos	Test whether quantized filters are composed of second-order sections
isstable	Test for stability of quantized filters
limitcycle	Detect limit cycles in a quantized filter
nlm	Use the Noise Loading Method to estimate the frequency response of a quantized filter
zplane	Compute a pole-zero plot for a quantized filter

Table 13-1: Quantized Filtering Functions

Function	Description
filter	Filter data with a quantized filter
normalize	Normalize quantized filter coefficients

Second-Order Sections Conversion Functions

Function	Description
cell2sos	Convert a cell array to a second-order sections matrix
sos	Convert a quantized filter to second-order sections form, order, and scale
sos2cell	Convert a second-order sections matrix to a cell array

Quantizer Construction and Property Functions 

Function	Description
bin2num	Convert binary string to number
get	Return the property values for a quantizer
num2bin	Convert a number to two's-complement binary string
num2hex	Convert a number to hexadecimal string
qreport	Returns the listing of a quantizer and its properties
quantize	Apply a quantizer to a data set
quantizer	Construct a quantizer object
reset	Reset the properties of a quantizer to their initial values
set	Set and display the property values of a quantizer
unitquantize	Set numbers between eps(q) and 1 equal to 1
wordlength	Return the wordlength of a quantizer

Quantizer Analysis Functions

Function	Description
denormalmax	Return the largest denormalized quantized number
denormalmin	Return the smallest denormalized quantized number
eps	Return the quantized relative accuracy of a quantizer
errmean	Return the mean of the quantization error resulting from quantizing a signal
errpdf	Calculate the probability density function (pdf) of the quantization error
errvar	Return the variance of the quantization error resulting from quantizing a signal
exponentbias	Return the exponent bias for a quantizer
exponentlength	Return the exponent length for a quantizer
exponentmax	Return the maximum exponent for a quantizer
exponentmin	Return the minimum exponent for a quantizer
fractionlength	Return the fraction length for a quantizer
isfixed	Test whether quantizers are fixed point
isfloat	Test whether quantizers are floating point
isnone	Test whether a quantizer has quantization mode equal to none
noverflows	Return the number of overflows encountered while using a quantizer on one or more data sets
range	Return the numerical range of a quantizer
realmax	Return the largest positive quantized number
realmin	Return the smallest positive quantized number
nunderflows	Return the number of underflows encountered while using a quantizer on one or more data sets

Quantized FFT Construction and Property Functions

Function	Description
fft	Apply a quantized FFT to a data set
get	Return the property values for a quantized FFT
ifft	Apply an inverse quantized FFT to a data set
qfft	Construct a quantized FFT
qreport	Returns the listing of a quantized FFT and its properties
quantizer	Return all the quantizers associated with a quantized FFT
reset	Reset the properties of a quantized FFT to their initial values
set	Set and display the property values of a quantized FFT
setbits	Set and one or more property values of a quantized FFT

Quantized FFT Analysis Functions

Function	Description
noverflows	Return the number of overflows resulting from the most recent application of a quantized FFT
range	Return the numerical range of a quantized FFT
twiddles	Return the twiddle factors for a quantized FFT

Filter Design Functions

Function	Description
cicdecimate	Use a cascaded integrator-comb (CIC) decimation filter to decrease the sampling rate for a signal
cicinterpolate	Use a cascaded integrator-comb (CIC) interpolation filter to increase the sampling rate for a signal
firceqrip	Design constrained, equiripple, finite impulse response (FIR) filters
firlpnorm	Design least-pth norm optimal FIR filters
firhalfband	Design half-band FIR filters
firminphase	Compute the minimum phase FIR spectral factor of linear phase FIR filters
firnyquist	Design lowpass Nyquist (L-th band) FIR filters
gremez	Design optimal equiripple FIR (finite impulse response) digital filters based on the Parks-McClellan algorithm
ifir	Design interpolated FIR filters
iircomb	Design comb IIR filters with periodic frequency response
iirgrpdelay	Design least-pth norm IIR filters with given group delay
iirlpnorm	Design least-pth norm IIR filters
iirlpnormc	Design constrained least-pth norm IIR filters
iirnotch	Design notch IIR filters to attenuate a fixed frequency
iirpeak	Design peaking IIR filters for boosting or cutting specific frequencies

Filter Conversion Functions

Function	Description
ca2tf	Convert coupled allpass filters to transfer function form
cl2tf	Convert lattice coupled allpass filters to transfer function form
firlp2lp	Transform lowpass FIR filters to lowpass filters with different passband specifications
firlp2hp	Transform lowpass FIR filters to highpass FIR filters
iirlp2bp	Transform lowpass IIR filters to bandpass filters
iirlp2bs	Transform lowpass IIR filters to bandstop filters
iirlp2hp	Transform lowpass IIR filters to highpass filters
iirlp2lp	Transform lowpass IIR filters to lowpass filters
iirpowcomp	Compute the power complementary IIR filter
tf2ca	Convert transfer function form to coupled allpass form
tf2cl	Convert transfer function form to lattice coupled allpass form

Adaptive Filter Design Functions and Their Initialization Functions

Function	Initializing Function	Description
adaptkalman	initkalman	Use a Kalman filter in an adaptive filtering application
adaptlms	initlms	Use a least mean squares (LMS) algorithm filter in an adaptive filtering application
adaptnlms	initnlms	Use a normalized LMS algorithm filter in an adaptive filtering application
adaptrls	initrls	Use a recursive least squares algorithm filter in an adaptive filtering application
adaptsd	initsd	Use a sign-data variant of the LMS algorithm filter in an adaptive filtering application
adaptse	initse	Use a sign-error variant of the LMS algorithm filter in an adaptive filtering application
adaptss	initss	Use a sign-sign variant of the LMS algorithm filter in an adaptive filtering application

Quantized FFT Properties Reference

Functions Operating on Quantized Filters