[Numpy-discussion] roots and high-order polynomial
Mon Jul 6 04:44:38 CDT 2009
Le vendredi 03 juillet 2009 à 10:00 -0600, Charles R Harris a écrit :
> What do you mean by erratic? Are the computed roots different from
> known roots? The connection between polynomial coefficients and
> polynomial values becomes somewhat vague when the polynomial degree
> becomes large, it is numerically ill conditioned.
For an illustration of what I mean by 'erratic', see
with the real part of the roots on the left, and the imaginary part of
- for low orders (<26), a pair of complex conjugate roots appears when
the order of polynomial is increased (with a step equal to 2). As
expected in my physical application, their real parts are negative.
- for higher order (>=26), there is no more 'hermitian
symmetry' (complex conjugate solutions), and real parts become
The computation of the coefficients of the polynomial is out of topic, I
already checked it and there is no errors.
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