给定一组坐标,实现三次Hermite差值曲线的绘制
时间: 2024-02-25 09:51:45 浏览: 77
好的,根据您的要求,我可以为您提供一个实现三次Hermite差值曲线的Python程序,代码如下:
```python
import matplotlib.pyplot as plt
import numpy as np
# 定义Hermite插值函数
def hermite_interpolation(x, y, dy):
n = len(x)
A = np.zeros((2*n, 2*n))
b = np.zeros((2*n, 1))
for i in range(n):
A[2*i][0] = 1
A[2*i+1][0] = 1
b[2*i] = y[i]
b[2*i+1] = y[i]
if i != 0:
A[2*i][2*i-1] = x[i]-x[i-1]
A[2*i+1][2*i-1] = x[i]-x[i-1]
A[2*i][2*i] = (x[i]-x[i-1])**2
A[2*i+1][2*i] = (x[i]-x[i-1])**2
if i != n-1:
A[2*i][2*i+1] = x[i+1]-x[i]
A[2*i+1][2*i+1] = x[i+1]-x[i]
A[2*i][2*i+2] = -(x[i+1]-x[i])**2
A[2*i+1][2*i+2] = -(x[i+1]-x[i])**2
for i in range(1, n-1):
A[2*i][2*n-2] = 3*(x[i]-x[i-1])**2
A[2*i+1][2*n-2] = 3*(x[i]-x[i-1])**2
A[2*i][2*n-1] = -3*(x[i+1]-x[i])**2
A[2*i+1][2*n-1] = -3*(x[i+1]-x[i])**2
b[2*i][0] = dy[i-1]
b[2*i+1][0] = dy[i]
A[2*n-2][1] = 1
A[2*n-1][2*n-2] = 1
return np.linalg.solve(A, b)
# 定义绘制函数
def plot_hermite(x, y, dy):
a = hermite_interpolation(x, y, dy)
n = len(x)
x_new = np.linspace(x[0], x[n-1], 1000)
y_new = np.zeros((1000, 1))
for i in range(1000):
for j in range(n-1):
if x_new[i] >= x[j] and x_new[i] <= x[j+1]:
y_new[i] = a[2*j] + a[2*j+1]*(x_new[i]-x[j]) + a[2*n-2]*(x_new[i]-x[j])**2 + a[2*n-1]*(x[j+1]-x_new[i])**2
break
plt.plot(x_new, y_new)
plt.scatter(x, y)
plt.show()
# 测试程序
x = [1, 2, 3, 4]
y = [8, 14, 15, 18]
dy = [3, 2, 5]
plot_hermite(x, y, dy)
```
您可以将自己的坐标点和一阶导数传入 `plot_hermite` 函数中进行绘制,例如:
```python
x = [1, 2, 3, 4]
y = [8, 14, 15, 18]
dy = [3, 2, 5]
plot_hermite(x, y, dy)
```
其中 `x` 和 `y` 分别为坐标点的横纵坐标,`dy` 为坐标点的一阶导数。程序会自动绘制出三次Hermite差值曲线。
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