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From: Jake Jarvis <pig_in_shoes@yahoo.com>
Newsgroups: comp.lang.java.programmer
Subject: Re: double == double
Date: Wed, 19 Oct 2016 16:36:32 +0200
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Am 19.10.2016 um 16:26 schrieb Jerry Stuckle:
> On 10/19/2016 9:32 AM, Eric Sosman wrote:
>> On 10/19/2016 9:03 AM, Mike Amling wrote:
>>> On 10/12/16 7:15 AM, Stefan Ram wrote:
>>>>   Sometimes it is taught that it makes no sense to compare
>>>>   two double values with »==«.
>>>>
>>>>   But what about this function?
>>>>
>>>> public static double max( final double a, final double b)
>>>> { return
>>>>   a == 0.0 && b == 0.0 && java.lang.Double.doubleToRawLongBits( a )
>>>>   == Double.doubleToRawLongBits( -0.0d )? b : a >= b ? a : b; }
>>>>
>>>>   which tries to return positive zero if one argument is
>>>>   positive zero and the other one negative zero?
>>>>
>>>>   It seems that there are special cases when a comparison
>>>>   of double values with »==« is appropriate. I have observed
>>>>   that this is usually the case when comparing with »0.0« -
>>>>   another example would be avoiding to divide by 0.0.
>>>
>>> If a==0.0 and b==0.0, there's no need to test whether either is -0.0.
>>> The function could be simplified to
>>>
>>> public static double max(final double a, final double b) {
>>>   return a==0.0 && b==0.0 ? 0.0 : (a>=b ? a : b);
>>> }
>>
>>     This would return +0.0 for max(-0.0, -0.0).
>>
>
> PMJI, but how do you figure? a==0.0 && b==0.0 would be false

No.

, so it
> would evaluate a>=b.  Since both are -0.0, it would return that value.
>