Re: What is the behaviour of double / float primitive == comparison?

>
> The == comparison will return true if the actual bits are the same. This
> will depend on how the calculations pan out: how will the numbers you're
> going to divide be represented in binary, and how will the result of the
> division between these two numbers be represented?
>
> Btw, half values happen to be perfect for binary to represent, since
> decimal .5 is "0.1" in floating binary. Decimal 0.1 is, however,
> impossible to represent in floating binary.
>

Thanks a lot :-)

> Use BigDecimal. Or multiply away the fraction part and do your
> calculations using integers. Exact real values (floating point!) are a
> lie anyway! (Your desk isn't 2 meters across..)
>

I will... if this is my choice... however I am the one maintaining
existing code and just like to understand if some critical function is
using "==" comparison on double...

> PS: don't use float in any case, use double.
>
> PPS: Even more hilarious is the effect of JIT on floating point
> calculations: at the compilation point, you suddenly get the precision
> of the native (math co-)processor instead of the interpreter. This might
> be higher than what the IEEE standard defines (and the interpreter
> gives), apparently in particular regarding the exponent. The 'strictfp'
> keyword can fix this particular issue, so that you get just as bad
> accuracy when it is compiled - this to ensure perfect portability across
> platforms.
>
This is very useful, in fact I have read the equals() method of
java.lang.Double but I don't know if double primitive do this
samething.

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