<p>我对下面的算法有个问题。让我困惑的是为什么<code>x = random.random()*2 -1</code>和{<cd2>}而不是简单地<code>x = random.random()</code>和{<cd4>}?完整代码如下:</p>
<pre><code>import random
NUMBER_OF_TRIALS= 1000000
numberOfHits = 0
for i in range(NUMBER_OF_TRIALS):
x = random.random()*2 -1
y = random.random()*2 -1
if x * x + y * y <=1:
numberOfHits +=1
pi = 4* numberOfHits / NUMBER_OF_TRIALS
print("PI is", pi)
</code></pre>