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From Phil Steitz <phil.ste...@gmail.com>
Subject Re: [math] Shoud OpenIntToDoubleHashMap get return NaN instead of 0 for key not found?
Date Fri, 02 Jan 2009 17:29:58 GMT
sebb wrote:
> On 02/01/2009, Luc Maisonobe <Luc.Maisonobe@free.fr> wrote:
>   
>> Phil Steitz a écrit :
>>
>>     
>>> I am still working through this class and the sparse matrix class that
>>>       
>>  > it was extracted from (thanks, Ismael and Sugit!), so I am not sure if
>>  > changing this would cause problems, but the current setup (returning 0
>>  > for missing keys) limits usefulness of this class.   I see how this is
>>  > convenient for sparse matrices; but I would see NaN as a more natural
>>  > return value for non-existent keys in the general case.  Alternatively,
>>  > I guess we could add another method get(int key, double missingReturn).
>>  >
>>  > Thoughts?
>>
>>
>> I had exactly the same thought while extracting the class.
>>  I also prefer to use Double.NaN for numbers that have never been
>>  initialized explicitly, but I also understand 0 is more logical in the
>>  special case of sparse matrices.
>>     
>
> +0 (I never used Math, but seems sensible)
>
>   
>>  What about having a configurable value for missing entries ? It should
>>  probably be configured at construction time (with a default value to
>>  Double.NaN if not specified) and never changed afterwards. In the case
>>  of sparse matrices, we should configure this value to 0.0.
>>     
>
> +1 to never changing the value - making it final would be best for
> thread safety.
>
>   
+1

Phil
>>  Luc
>>
>>
>>  >
>>  > Phil
>>  >
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>>     
>
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