numpy.roots()

numpy.roots(p) [source]

Return the roots of a polynomial with coefficients given in p.

The values in the rank-1 array p are coefficients of a polynomial. If the length of p is n+1 then the polynomial is described by:

p[0] * x**n + p[1] * x**(n-1) + ... + p[n-1]*x + p[n]

Parameters:

Parameters:	p : array_like Rank-1 array of polynomial coefficients.
Returns:	out : ndarray An array containing the complex roots of the polynomial.
Raises:	ValueError When `p` cannot be converted to a rank-1 array.

p : array_like

Rank-1 array of polynomial coefficients.

Returns:

out : ndarray

An array containing the complex roots of the polynomial.

Raises:

ValueError

When p cannot be converted to a rank-1 array.

The algorithm relies on computing the eigenvalues of the companion matrix [R279].

[R279]

(1, 2) R. A. Horn & C. R. Johnson, Matrix Analysis. Cambridge, UK: Cambridge University Press, 1999, pp. 146-7.

>>> coeff = [3.2, 2, 1]
>>> np.roots(coeff)
array([-0.3125+0.46351241j, -0.3125-0.46351241j])

Links:

doc_NumPy

2017-01-10 18:18:33

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