Python:查找非线性方程的多个根 [英] Python: Finding multiple roots of nonlinear equation

问题描述

承担以下功能:

f(x) = x * cos(x-4)

使用x = [-2.5, 2.5]时，此功能在f(0) = 0和f(-0.71238898) = 0处交叉0.

With x = [-2.5, 2.5] this function crosses 0 at f(0) = 0 and f(-0.71238898) = 0.

这是通过以下代码确定的:

This was determined with the following code:

import math
from scipy.optimize import fsolve
def func(x):
    return x*math.cos(x-4)
x0 = fsolve(func, 0.0)
# returns [0.]
x0 = fsolve(func, -0.75)
# returns [-0.71238898]

使用fzero(或任何其他Python根查找器)在一次调用中找到两个根的正确方法是什么?有其他的scipy函数可以做到这一点吗?

What is the proper way to use fzero (or any other Python root finder) to find both roots in one call? Is there a different scipy function that does this?

fzero参考

推荐答案

定义函数，使其可以使用标量或numpy数组作为参数:

Define your function so that it can take either a scalar or a numpy array as an argument:

>>> import numpy as np
>>> f = lambda x : x * np.cos(x-4)

然后将参数向量传递给fsolve.

Then pass a vector of arguments to fsolve.

>>> x = np.array([0.0, -0.75])
>>> fsolve(f,x)
array([ 0.        , -0.71238898])

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