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Code: Alles auswählen

# Lagrange Interpolation NA

import matplotlib.pyplot as plt
import numpy as np
#import sympy as sp
from sympy import *
#from numpy import arange

x = (-2.5, -1., 0.5, 2., 3.5)
y = (0.,3., 3.5, 0., -2.5)
L = np.zeros(len(x)-1)
p = 0.0
a = Symbol('a')
print a

print L

for i in range (0, len(x)-1):
    L[i] = 1
    print L
    for j in range (0, len(x)):
        if i != j:
            L[i] = L[i]*((a-x[j])/(x[i]-x[j]))
            print L
    p = p + y[i]*L[i]
print p

Code: Alles auswählen

%run "C:\Users\FabSel\..."
a
[ 0.  0.  0.  0.]
[ 1.  0.  0.  0.]
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
C:\Users\FabSel... in <module>()
     21     for j in range (0, len(x)):
     22         if i != j:
---> 23             L[i] = L[i]*((a-x[j])/(x[i]-x[j]))
     24             print L
     25     p = p + y[i]*L[i]

C:\Users\FabSel\AppData\Local\Enthought\Canopy\User\lib\site-packages\sympy\core\expr.pyc in __float__(self)
    223         if result.is_number and result.as_real_imag()[1]:
    224             raise TypeError("can't convert complex to float")
--> 225         raise TypeError("can't convert expression to float")
    226 
    227     def __complex__(self):

TypeError: can't convert expression to float