功能

所有函数都支持下面记录的方法，继承自 sympy.core.function.Function .

class sympy.core.function.Function(*args)

应用数学函数的基类。

它还充当未定义函数类的构造函数。

See the Writing Custom Functions guide for details on how to subclass Function and what methods can be defined.

实例

Undefined Functions

To create an undefined function, pass a string of the function name to Function.

>>> from sympy import Function, Symbol
>>> x = Symbol('x')
>>> f = Function('f')
>>> g = Function('g')(x)
>>> f
f
>>> f(x)
f(x)
>>> g
g(x)
>>> f(x).diff(x)
Derivative(f(x), x)
>>> g.diff(x)
Derivative(g(x), x)

Assumptions can be passed to Function the same as with a Symbol. Alternatively, you can use a Symbol with assumptions for the function name and the function will inherit the name and assumptions associated with the Symbol:

>>> f_real = Function('f', real=True)
>>> f_real(x).is_real
True
>>> f_real_inherit = Function(Symbol('f', real=True))
>>> f_real_inherit(x).is_real
True

Note that assumptions on a function are unrelated to the assumptions on the variables it is called on. If you want to add a relationship, subclass Function and define custom assumptions handler methods. See the Assumptions section of the Writing Custom Functions guide for more details.

Custom Function Subclasses

The Writing Custom Functions guide has several Complete Examples of how to subclass Function to create a custom function.

as_base_exp()

将方法作为2元组（基、指数）返回。

fdiff(argindex=1)

返回函数的一阶导数。

classmethod is_singular(a)

测试参数是本质奇点还是分支点，或者函数是非全纯的。

目录

• 初级
• 组合
• 枚举
• 特殊的