擅长:python、mysql、java
<p>您忘记在<code>cov</code>中定义<code>summation</code>,并且忘记将<code>summation</code>添加到新的总和中。
请尝试以下方法:</p>
<pre class="lang-py prettyprint-override"><code>def cov(a, b):
a_mean = np.mean(a)
b_mean = np.mean(b)
# Added summation and assigned 0 to it, like for sum in cov1
summation = 0
for i in range(0, a.size):
# Added + summation here, just like in cov1
summation = np.sum((a[i] - a_mean) * (b[i] - b_mean)) + summation
return summation/(len(a)-1)
</code></pre>