<p>我正在使用Python 3.6。<br/>
我真的很困惑,为什么会这样?</p>
<pre><code>In [1]: import numpy as np
In [2]: a = np.array(-1)
In [3]: a
Out[3]: array(-1)
In [4]: a ** (1/3)
/Users/wonderful/anaconda/bin/ipython:1: RuntimeWarning: invalid value encountered in power
#!/Users/wonderful/anaconda/bin/python
Out[4]: nan
</code></pre>