[samigo-team] Floating point numbers

[Sam Ottenhoff]

I gave it a try, but it involves 1000+ changes.  It probably makes sense to
just improve precision and move from floats to doubles instead.  The
gradebook records POINTS_EARNED as a double.


On Thu, Feb 28, 2013 at 2:16 PM, Karen Tsao <ktsao at stanford.edu> wrote:

> Thanks for everyone's input.
>
> Sam,
>
> Could you please make the change? Thanks!
>
> Karen
>
>
> On Thu, Feb 28, 2013 at 6:19 AM, David Horwitz <david.horwitz at uct.ac.za>wrote:
>
>>  There's a another issue (fixable without replacing floats but still)
>>
>> There are several places in the code where direct foat comparisons are
>> made:
>>
>> Float a =
>> Float b,
>>
>> if (a.equals(b))
>>
>> For instance to check if an answer has been updated etc. We could be
>> getting extra updated because of slight differences in the float
>> representation ...
>>
>> D
>>
>>
>> On Thu, 2013-02-28 at 09:11 -0500, Sam Ottenhoff wrote:
>>
>>
>>  But just curious, what is the advantage of this change? Is this for
>> getting a more precise score? Like some 0.999 issue?
>>
>>
>>
>>  An instructor created a complex placement exam that used point scores
>> in the millions, thousands, hundreds, etc. as a way of being able to
>> quickly see points in various sections in the final score (example:
>> 27005508.06 could be broken up to see that the student scores 06 on sec 1,
>> 08, on sec 2, 55 on sec 3, 27 on sec 4).
>>
>>
>>
>>  So the reason why floating point numbers aren't used for money:
>>
>>
>>
>>  > create table floattest (z float);
>>
>> > insert into floattest VALUES (*2075808*);
>>
>> > select * from floattest;
>>
>>
>>
>>  The result: *2075810*
>>
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