用 python 编写一个使任意一元四次函数的程序,要求进退法单谷ξ<0.01黄金分割法求极小值
时间: 2024-10-08 11:06:42 浏览: 44
要编写一个Python程序,使用进退法(也称为Brent's method)或黄金分割搜索法(Golden Section Search)寻找一元四次函数的最小值,首先需要定义一个函数来表示四次函数,并实现这两种数值优化算法。以下是一个基本的示例:
```python
import math
# 定义四次函数 f(x) = ax^4 + bx^3 + cx^2 + dx + e
def quartic_function(a, b, c, d, e, x):
return a * x**4 + b * x**3 + c * x**2 + d * x + e
# 进退法(Brent's method)
def bisection_search(f, lower_bound, upper_bound, tolerance=0.01):
if lower_bound > upper_bound:
raise ValueError("Lower bound must be less than upper bound")
while (upper_bound - lower_bound) >= tolerance:
mid = (lower_bound + upper_bound) / 2
if f(mid) == 0 or (f(lower_bound) * f(mid) <= 0): # 如果满足零点条件或区间改变方向
upper_bound = mid
else:
lower_bound = mid
return mid
# 黄金分割法
def golden_section_search(f, a, b, tolerance=0.01, golden_ratio=(math.sqrt(5) - 1) / 2):
while abs(b - a) >= tolerance:
ratio = 1 - golden_ratio
pa = a + golden_ratio * (b - a)
pb = a + ratio * (b - a)
if f(pa) < f(pb):
b = pb
else:
a = pa
return (a + b) / 2
# 示例一元四次函数
a = 1
b = -3
c = 2
d = -1
e = 0
func = lambda x: quartic_function(a, b, c, d, e, x)
# 使用进退法求解
min_value_brents = bisection_search(func, -10, 10)
print(f"Using Brent's method: Min value is {min_value_brents}, at x={func(min_value_brents)}")
# 使用黄金分割法求解
min_value_golden = golden_section_search(func, -10, 10)
print(f"Using Golden Section search: Min value is {min_value_golden}, at x={func(min_value_golden)}")
阅读全文
相关推荐
![zip](https://img-home.csdnimg.cn/images/20241231045053.png)
![pdf](https://img-home.csdnimg.cn/images/20241231044930.png)
![pdf](https://img-home.csdnimg.cn/images/20241231044930.png)
![pdf](https://img-home.csdnimg.cn/images/20241231044930.png)
![application/msword](https://img-home.csdnimg.cn/images/20210720083327.png)
![pdf](https://img-home.csdnimg.cn/images/20241231044930.png)
![-](https://img-home.csdnimg.cn/images/20241231044937.png)
![-](https://img-home.csdnimg.cn/images/20241231044937.png)
![-](https://img-home.csdnimg.cn/images/20241231044937.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)
![](https://csdnimg.cn/download_wenku/file_type_ask_c1.png)