我正在使用https://symfit.readthedocs.io/en/master/examples/ex_fourier_series.html上提供的示例代码来计算给定函数的傅立叶级数。但是，在我成功安装包symfit并开始运行示例代码后，出现错误：ImportError: cannot import name 'parameters'在代码的第一行from symfit import parameters, variables, sin, cos, Fit。显然'parameters'是symfit包中的一个对象，但我不知道为什么它告诉我'parameters'找不到对象。示例代码如下：
from symfit import parameters, variables, sin, cos, Fit
import numpy as np
import matplotlib.pyplot as plt
def fourier_series(x, f, n=0):
"""
Returns a symbolic fourier series of order `n`.
:param n: Order of the fourier series.
:param x: Independent variable
:param f: Frequency of the fourier series
"""
# Make the parameter objects for all the terms
a0, *cos_a = parameters(','.join(['a{}'.format(i) for i in range(0, n + 1)]))
sin_b = parameters(','.join(['b{}'.format(i) for i in range(1, n + 1)]))
# Construct the series
series = a0 + sum(ai * cos(i * f * x) + bi * sin(i * f * x)
for i, (ai, bi) in enumerate(zip(cos_a, sin_b), start=1))
return series
x, y = variables('x, y')
w, = parameters('w')
model_dict = {y: fourier_series(x, f=w, n=3)}
print(model_dict)
# Make step function data
xdata = np.linspace(-np.pi, np.pi)
ydata = np.zeros_like(xdata)
ydata[xdata > 0] = 1
# Define a Fit object for this model and data
fit = Fit(model_dict, x=xdata, y=ydata)
fit_result = fit.execute()
print(fit_result)
# Plot the result
plt.plot(xdata, ydata)
plt.plot(xdata, fit.model(x=xdata, **fit_result.params).y, ls=':')
plt.xlabel('x')
plt.ylabel('y')
plt.show()
感谢您阅读我的问题！