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group Scilab Group Scilab Function group
NAME
group - group delay for digital filter
CALLING SEQUENCE
[tg,fr]=group(npts,a1i,a2i,b1i,b2i)
PARAMETERS
npts : integer : number of points desired in calculation of group
delay
a1i : in coefficient, polynomial, rational polynomial, or cascade
polynomial form this variable is the transfer function of the
filter. In coefficient polynomial form this is a vector of
coefficients (see below).
a2i : in coeff poly form this is a vector of coeffs
b1i : in coeff poly form this is a vector of coeffs
b2i : in coeff poly form this is a vector of coeffs
tg : values of group delay evaluated on the grid fr
fr : grid of frequency values where group delay is evaluated
DESCRIPTION
Calculate the group delay of a digital filter with transfer function
h(z).
The filter specification can be in coefficient form, polynomial form,
rational polynomial form, cascade polynomial form, or in coefficient
polynomial form.
In the coefficient polynomial form the transfer function is formulated by
the following expression
h(z)=prod(a1i+a2i*z+z**2)/prod(b1i+b2i*z+z^2)
EXAMPLE
z=poly(0,'z');
h=z/(z-.5);
[tg,fr]=group(100,h);
plot(fr,tg)
AUTHOR
C. B.
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