擅长:python、mysql、java
<p>使用<a href="http://docs.python.org/2/library/string.html#format-string-syntax" rel="nofollow">string formatting</a>并将<code>userDecimals</code>传递给<a href="http://docs.python.org/2/library/string.html#format-specification-mini-language" rel="nofollow">format specifier</a>的<code>precision</code>部分:</p>
<pre><code>>>> import math
>>> userDecimals = 6
>>> '{:.{}f}'.format(math.sqrt(1 - .1 **2), userDecimals)
'0.994987'
>>> userDecimals = 10
>>> '{:.{}f}'.format(math.sqrt(1 - .1 **2), userDecimals)
'0.9949874371'
</code></pre>