[英]Python Square Root doesn't work
How come when I run this function it prints 3 and 4 alternating an infinite number of times. 当我运行此功能时,为什么它会无限次打印3和4。 I can't understand why it keeps going, and also shouldn't it at least print 5 initially?
我不明白为什么它会继续下去,而且它不应该至少最初打印5张吗?
a = 15
x = 5
while True:
print x
y = (x + a/x) / 2
if y == x:
break
x = y
You are doing integer division. 您正在做整数除法。 Change your constants to
将常量更改为
a = 15.0
x = 5.0
Also, since the numbers will be float
check for some allowable precision, instead of trying to use exact equality. 另外,由于数字将是
float
请检查一些允许的精度,而不要尝试使用完全相等的形式。
while True:
print x
y = (x + a/x)/2
if abs(y - x) < 0.0001:
break
x = y
Output 输出量
5
4.0
3.875
3.87298387097
I can tell you are using python 2, so /
in this case integer division. 我可以告诉您正在使用python 2,因此
/
在这种情况下为整数除法。 In order to force floating point division, there are a few ways you could do it, but this is probably the easiest. 为了强制进行浮点除法,有几种方法可以做到,但这可能是最简单的。
y = (x + 1.0 * a / x) / 2
I hope this small code trace will help you see the error: 我希望这个小的代码跟踪可以帮助您看到错误:
First Loop 第一循环
y= (5 + (15/5) ) /2
y= (5 + 3) /2
y=4
4 !=5
x=4
second loop 第二循环
y= (4+(15/4))/2
y= (4+3)/2
y=3
3!=4
x=3
third loop 第三循环
y=(3+(15/3)) /2
y=(3+5) /2
y=8/2
y=4
4!=3
x=4
will repeat... 将重复...
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