F(x)=[(x2)-(5.1/4*π**21)*(x1)**2+(5/π)*(x1)-6]**2+10*(1-1/8*π)*cos(x1)+10用梯度下降法求最小值
时间: 2023-12-06 13:05:10 浏览: 98
以下是使用梯度下降法求解F(x)最小值的Python代码:
```python
import numpy as np
# 定义函数F(x)
def F(x):
x1, x2 = x
return (x2 - (5.1 / (4 * np.pi ** 2)) * x1 ** 2 + (5 / np.pi) * x1 - 6) ** 2 + 10 * (1 - 1 / (8 * np.pi)) * np.cos(x1) + 10
# 定义函数F(x)的梯度
def grad_F(x):
x1, x2 = x
grad_x1 = 2 * (x2 - (5.1 / (4 * np.pi ** 2)) * x1 ** 2 + (5 / np.pi) * x1 - 6) * ((5.1 / (2 * np.pi ** 2)) * x1 + (5 / np.pi) * np.sin(x1) - 10 / (8 * np.pi) * np.sin(x1))
grad_x2 = 2 * (x2 - (5.1 / (4 * np.pi ** 2)) * x1 ** 2 + (5 / np.pi) * x1 - 6)
return np.array([grad_x1, grad_x2])
# 定义梯度下降函数
def gradient_descent(F, grad_F, init_x, lr=0.01, max_iter=10000, tol=1e-6):
x = init_x
for i in range(max_iter):
grad = grad_F(x)
if np.linalg.norm(grad) < tol:
break
x -= lr * grad
return x, F(x)
# 设置初始点并调用梯度下降函数求解最小值
init_x = np.array([0, 0])
min_x, min_val = gradient_descent(F, grad_F, init_x)
# 输出最小值及对应的x值
print("最小值为:", min_val)
print("对应的x值为:", min_x)
```
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