使用quad方法python进行集成

Question

我尝试使用scipy重现错误函数，而不是使用erf方法。

这是我的代码：

#!/usr/bin/env python
import numpy as np
import math
from scipy.integrate import quad

def error_func(y):
    return 2/math.sqrt(np.pi)*quad(np.exp(-y**2), 1, np.inf, args=(y))[0]

g = [error_func(x) for x in np.arange(-1,1,0.2)]

print g

此代码返回以下错误消息：

File "./test.py", line 9, in <module>
    g = [error_func(x) for x in np.arange(-1,1,0.2)]
  File "./test.py", line 7, in error_func
    return 2/math.sqrt(np.pi)*quad(np.exp(-y**2), 1, np.inf, args=(y))[0]
  File "/usr/local/lib/python2.7/site-packages/scipy/integrate/quadpack.py", line 316, in quad
    points)
  File "/usr/local/lib/python2.7/site-packages/scipy/integrate/quadpack.py", line 383, in _quad
    return _quadpack._qagie(func,bound,infbounds,args,full_output,epsabs,epsrel,limit)
quadpack.error: quad: first argument is not callable

如果我没理解错的话，quad的第一个参数必须是一个函数。我想我考对了。我的代码出了什么问题？