numpy.polyval() in Python (original) (raw)

Last Updated : 29 Nov, 2018

numpy.polyval(p, x) method evaluates a polynomial at specific values.

If ‘N’ is the length of polynomial ‘p’, then this function returns the value

**Parameters :**
p : [array_like or poly1D] polynomial coefficients are given in decreasing order of powers. If the second parameter (root) is set to True then array values are the roots of the polynomial equation.
For example : poly1d(3, 2, 6) = 3x2 + 2x + 6

x : [array_like or poly1D] A number, an array of numbers, for evaluating ‘p’.

**Return:** Evaluated value of polynomial.

Code : Python code explaining polyval()

import numpy as np

import pandas as pd

p1 = np.poly1d([ 1 , 2 ])

p2 = np.poly1d([ 4 , 9 , 5 , 4 ])

print ( "P1 : " , p1)

print ( "\n p2 : \n" , p2)

print ( "\n\np1 at x = 2 : " , p1( 2 ))

print ( "p2 at x = 2 : " , p2( 2 ))

a = np.polyval([ 1 , 2 ], 2 )

b = np.polyval([ 4 , 9 , 5 , 4 ], 2 )

print ( "\n\nUsing polyval" )

print ( "p1 at x = 2 : " , a)

print ( "p2 at x = 2 : " , b)

c = np.polyval(np.poly1d([ 4 , 9 , 5 , 4 ]), np.poly1d( 2 ))

print ( "\nc : " , c)

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