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numpy
matplotlib
ipykernel

61
src/serie_3.py Normal file
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# %%
import numpy as np
import matplotlib.pyplot as plt
# %%
print(60 * "-")
print(__file__)
print("Aufgabe 2. Interpolationspolynome gemäss NEWTON-Schema berechnen")
# punkte [[x0, x1, x2, xn], [y0, y1, y2, yn]]
punkte = [
[np.array([4, 8]), np.array([1, -1])],
[np.array([-1, 1, 2]), np.array([15, 5, 9])],
[np.array([-1, 0, 1, 2]), np.array([-5, -1, -1, 1])],
]
for punkt in punkte:
# Parameter
x_data = punkt[0]
y_data = punkt[1]
x_0 = x_data[0]
x_E = x_data[-1]
N = 201
lw = 3
fig = 1
# Berechnung
n = np.size(y_data)
TAB = np.block([[y_data], [np.zeros((n - 1, n))]])
c_data = np.zeros(n)
c_data[0] = y_data[0]
for i in range(1, n):
for j in range(1, n):
TAB[i][j] = (TAB[i - 1][j] - TAB[i - 1][j - 1]) / (
x_data[j] - x_data[j - i]
)
c_data[i] = TAB[i][i]
# Funktionen:
def p(x):
d = 1
y = c_data[0]
for k in range(1, n):
d = d * (x - x_data[k - 1])
y = y + c_data[k] * d
return y
# Daten
u_data = np.linspace(x_0, x_E, N)
v_data = p(u_data)
fh = plt.figure(fig)
plt.plot(u_data, v_data, linewidth=lw)
plt.plot(x_data, y_data, "o", linewidth=lw)
plt.xlabel(r"$x$")
plt.ylabel(r"$y$")
plt.grid(visible=True)
plt.axis("image")
print(60 * "-")