title: Integrate with scipy
body: <p>I want to integrate <code>x**(-2/3)*(x-1)**(1/3)</code> from 0~1, I had changed variables and use Simpson rule to solve it before,and now I want to try some quicker methods.</p>
  
  <p>my code: </p>
  
  <pre><code>x1 = lambda x: x**(-2/3)*(x-1)**(1/3)
  integrate.quad(x1,0,1)
  </code></pre>
  
  <p>Error:</p>
  
  <pre><code>Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
    File "/usr/lib/python3/dist-packages/scipy/integrate/quadpack.py", line 281, in quad
      retval = _quad(func,a,b,args,full_output,epsabs,epsrel,limit,points)
    File "/usr/lib/python3/dist-packages/scipy/integrate/quadpack.py", line 345, in _quad
      return _quadpack._qagse(func,a,b,args,full_output,epsabs,epsrel,limit)
  quadpack.error: Supplied function does not return a valid float.
  </code></pre>
  
  <p>How can I solve it?</p>