[Numpy-discussion] Problem with roots and complex coefficients
lorenzo bolla
lbolla@gmail....
Thu Apr 19 10:34:53 CDT 2007
dear all,
I've some problems with numpy.roots.
take a look at the following code:
========================================
import numpy
OK = numpy.roots([1, 1, 1])
OK = numpy.roots([1j, 1])
KO = numpy.roots([1, 1j, 1])
========================================
it fails with this error message, trying to execute the last line:
TypeError: can't convert complex to float; use
abs(z)/usr/lib/python2.4/site-packages/numpy/lib/polynomial.py in roots(p)
119 if N > 1:
120 # build companion matrix and find its eigenvalues (the
roots)
--> 121 A = diag(NX.ones((N-2,), p.dtype), -1)
122 A[0, :] = -p[1:] / p[0]
123 roots = _eigvals(A)
/usr/lib/python2.4/site-packages/numpy/lib/twodim_base.py in diag(v, k)
66 i = arange(0,n+k)
67 fi = i+(i-k)*n
---> 68 res.flat[fi] = v
69 return res
70 elif len(s)==2:
TypeError: can't convert complex to float; use abs(z)
any ideas?
thanks,
Lorenzo
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