# [SciPy-user] Characteristic polynomial

Bryan Van de Ven bryanv@enthought....
Tue Dec 11 09:37:37 CST 2007

```In [16]: numpy.lib.poly?
Type:           function
Base Class:     <type 'function'>
String Form:    <function poly at 0xb7a66224>
Namespace:      Interactive
File:
/workspace/python2.5/lib/python2.5/site-packages/numpy/lib/polynomial.py
Definition:     numpy.lib.poly(seq_of_zeros)
Docstring:
Return a sequence representing a polynomial given a sequence of roots.

If the input is a matrix, return the characteristic polynomial.

Example:

>>> b = roots([1,3,1,5,6])
>>> poly(b)
array([ 1.,  3.,  1.,  5.,  6.])

In [17]: a = array([[1,0],[0,2]])

In [18]: coeffs = numpy.lib.poly(a)

In [19]: numpy.lib.poly1d(coeffs)
Out[19]: poly1d([ 1., -3.,  2.])

Nikolas Karalis wrote:
> Hello... I'm trying to compute the characteristic polynomial of an
> integer (numpy) matrix. But i cannot find any way of doing this.
> Do you have any ideas/suggestions?
>
> --
> Nikolas Karalis
> Applied Mathematics and Physics Undergraduate
> National Technical University of Athens, Greece
> http://users.ntua.gr/ge04042
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> SciPy-user mailing list
> SciPy-user@scipy.org
> http://projects.scipy.org/mailman/listinfo/scipy-user

```