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numpy.polyval() in Python

  • 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()




# Python code explaining 
# numpy.polyval()
    
# importing libraries
import numpy as np
import pandas as pd
    
# Constructing polynomial 
p1 = np.poly1d([1, 2]) 
p2 = np.poly1d([4, 9, 5, 4]) 
    
print ("P1 : ", p1) 
print ("\n p2 : \n", p2) 


 




# Solve for x = 2 
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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