Python中的 numpy.polyval()

numpy.polyval(p, x)方法计算特定值的多项式。

如果“N”是多项式“p”的长度，则此函数返回值

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.

代码：解释 polyval() 的Python代码

# 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)