Equalize lengths of transfer function's numerator and denominator
[b,a] = eqtflength(num,den)
[b,a,n,m] = eqtflength(num,den)
[b,a] = eqtflength(num,den) modifies
the vector num and/or the vector den, so that the
resulting output vectors b and a have the same
length. The input vectors num and den may have
different lengths. The vector num represents the numerator polynomial
of a given discrete-time transfer function, and the vector den
represents its denominator. The resulting numerator b and denominator
a represent the same discrete-time transfer function, but these
vectors have the same length.
[b,a,n,m] = eqtflength(num,den)
modifies the vectors as above and also returns the numerator order n
and the denominator m, not including any trailing zeros.
Use eqtflength to obtain a numerator and denominator of equal
length before applying transfer function conversion functions such as tf2ss and tf2zp to discrete-time models.
num = [1 0.5]; den = [1 0.75 0.6 0]; [b,a,n,m] = eqtflength(num,den);
eqtflength(num,den) appends zeros to either num
or den as necessary. If both num and
den have trailing zeros in common, these are removed.