fromfunction函数的几个参数的含义是什么啊？为什么我把书上2.2.3节的代码敲到PyCharm里面系统报错说：

Traceback (most recent call last):
  File "C:/Users/zhang/PycharmProjects/dazhiSciProg/Chapter2Numpy/2.2.3.py", line 9, in <module>
    tri_ufunc1=np.fromfunction(triangle_wave,4,1)
TypeError: fromfunction() takes exactly 2 arguments (3 given)

原代码如下：

import numpy as np
x=np.linspace(0,2,1000)
def triangle_wave(x,c,c0,hc):
    x=x-int(x)
    if x>=c:r=0.
    elif x<=c0:r=x/c0*hc
    else: r=(c-x)/(c-c0)*hc
    return r
tri_ufunc1=np.fromfunction(triangle_wave,4,1)
y=tri_ufunc1(x,0.6,0.4,1.0)