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.

See also

poly: Find the coefficients of a polynomial with a given sequence of roots.
polyval: Evaluate a polynomial at a point.
polyfit: Least squares polynomial fit.
poly1d: A one-dimensional polynomial class.

Notes

The algorithm relies on computing the eigenvalues of the companion matrix [R243].

References

[R243]

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

Examples

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