# -*- coding: utf-8 -*-

import numpy as np

x=np.array([0,2,3],float)
y=np.array([7,11,28],float)
xp=float(input('Enter x:'))  #defined yp as 0 for starting.Actually yp is the summation so


def interpolate(xp):#It can be written in xp=float(value).
    
        #we will use summation loop so the intial value of the summation should
        #start from zero 
    yp=0
                        #zip: When calculating xi, it is used to put the x 
                        #and y values in order.
                        
    for xi,yi in zip(x,y):  #thanks to prod: can use to xi for loop in this and two variables
        print(xi,yi)
        yp +=yi*np.prod((xp-x[x !=xi])/(xi-x [x !=xi]))   # martix array multiplication
                                 #x !=xi :do not include the calculated term in the formula.    
    return yp


#xp=3

print('For x=%.2f,y=%f' % (xp,interpolate(xp)))