[Scipy-tickets] [SciPy] #651: Bug fixed for scipy.signal.tf2zpk
SciPy
scipy-tickets@scipy....
Sun Apr 20 05:35:43 CDT 2008
#651: Bug fixed for scipy.signal.tf2zpk
----------------------------+-----------------------------------------------
Reporter: bow_der_kleine | Owner: somebody
Type: enhancement | Status: new
Priority: normal | Milestone: 0.7
Component: Other | Version:
Severity: normal | Keywords:
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Function scipy.signal.tf2zpk in file ./signal/filter_design.py has a bug.
If the length of input coefficients is too long, then the outputs zeros
and poles are wrong. The reason for this bug is function normalize(). I
eliminated this line of code and function scipy.signal.tf2zpk works pretty
good. Following is my bug fixed.
{{{
def tf2zpk(b,a):
"""Return zero, pole, gain (z,p,k) representation from a numerator,
denominator representation of a linear filter.
"""
# b,a = normalize(b,a)
b = (b+0.0) / a[0]
a = (a+0.0) / a[0]
k = b[0]
b /= b[0]
z = roots(b)
p = roots(a)
return z, p, k
}}}
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Ticket URL: <http://scipy.org/scipy/scipy/ticket/651>
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