Question

试图用一块石头杀死两只鸟我决定编写一些代码，让我同时练习python和微积分。我有两个单独的文件，Derivative.py和newton_method.py（我知道我应该更好地命名我的文件）。 Derivatibe.py的文本如下

def fx(value, function):
    x = value
    return eval(function)

def function_input(input):
    function = str(input)
    return function

def derivative_formula(x, h):
    return (fx(x - h, input_function) - fx(x + h, input_function)) / (2.0 * h)

def derivative_of_x(x):
    error = 0.0001
    h = 0.1
    V = derivative_formula(x, h)
    print V
    h = h / 2.0
    derivative_estimate = derivative_formula(x, h)
    while abs(derivative_estimate - V) < error:
        V = derivative_formula(x, h)
        h = h / 2.0
        derivative_estimate = derivative_formula(x, h)
        print derivative_estimate
    return derivative_estimate

来自newton_method.py的文字是：

from Derivative import *

input_function = function_input(raw_input('enter a function with correct python syntax'))

E = 1 * (10 ** -10)

guessx = float(raw_input('Enter an estimate'))

def newton_method(guessx, E, function):
    x1 = guessx
    x2 = x1 - (fx(x1, input_function) / derivative_of_x(x1))
    while x2 - x1 < E:
        x1 = x2
        x2 = x1 - (fx(x1, input_function) / derivative_of_x(x1))
    return x2

print "The root of that function is %f" % newton_method(guessx, E, input_function)

错误：

Traceback (most recent call last):
  File "newton_method.py", line 17, in <module>
    print "The root of that function is %f" % newton_method(guessx, E,         input_function)
  File "newton_method.py", line 11, in newton_method
    x2 = x1 - (fx(x1, input_function) / derivative_of_x(x1))
  File "C:\Users\159micarn\Desktop\Python\Derivative.py", line 15, in derivative_of_x
    V = derivative_formula(x, h)
  File "C:\Users\159micarn\Desktop\Python\Derivative.py", line 10, in derivative_formula
    return (fx(x - h, input_function) - fx(x + h, input_function)) / (2.0 * h)
NameError: global name 'input_function' is not defined

我是否需要在Derivative.py中声明input_function？我原本以为在newton_method.py中声明它就足够了。

Answer 1

模块无权访问导入它们的模块的命名空间。想象一下导入Derivative.py的10个模块。它会使用哪个input_function？ input_function只是另一个值，应该是derivative_formula的附加输入参数。

导入函数时全局名称错误

1 个答案: