PYTHON 符号不可调用

PYTHON Symbol is not callable

我开始学习 Python 微分方程和差分方程,这是来自 SymPy 教程,但我仍然收到此错误:'Symbol' object is not callable. 我该如何解决这个问题?

t = symbols('t',real=True)

x, y = symbols('x, y', function=True)

eq = (Eq(Derivative(x(t),t), 12*t*x(t) + 8*y(t)), Eq(Derivative(y(t),t), 21*x(t) + 7*t*y(t)))

如果我对 docs 的解释正确,你的例子应该定义如下:

from sympy import Function

t = symbols('t',real=True)

x = Function('x')(t)
y = Function('y')(t)

eq = (Eq(Derivative(x,t), 12*t*x + 8*y), 
      Eq(Derivative(y,t), 21*x + 7*t*y))