Learn the numpy roots() function with code examples

Posted on Apr 08, 2022

Learn how to use the numpy roots function in Python


The numpy roots() function is used to find the roots of a polynomial equation using the coefficient values.

The syntax of the function is as follows:

numpy.roots([n])

The roots accept an array of polynomial coefficients as [n, n, ...] and return the roots of the equation.

If the array length is n+1 then the polynomial is described by:

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

For example, if you have the following equation: x2 - 5x + 6

The coefficients are 1, -5, and 6.

Use the root() function to solve find the roots:

import numpy as np

np.roots([1, -5, 6])

# array([3., 2.])

So x = 3, 2

You can also pass a floating number as one of the coefficient values:

import numpy as np

coeff = [3.7, 2, 1]

np.roots(coeff)

The output will be:

array([-0.27027027+0.44409937j, -0.27027027-0.44409937j])

And that’s how the numpy.roots() function works.

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