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From Pedro Giffuni <...@apache.org>
Subject Re: Incompatible changes in AOO 4.0 ?
Date Mon, 31 Dec 2012 15:08:43 GMT
Hello Regina;


I looked into the AOO code and the situation is actually a less critical than
I thought: we don't use the system libraries for the hyperbolic functions but
instead we have our own implementations in the SAL layer.

----- Messaggio originale -----
> Da: Regina Henschel

> 
> Hi Pedro, hi Andrew,
> 
> Pedro Giffuni schrieb:
...
>> 
>>  I did just a very small set of changes for asinh, acosh, atanh and a some
>>  internal power functions .. just for testing.
>> 
>>  Since there is interest in this I opened a Bugzilla issue with the patch:
>>  https://issues.apache.org/ooo/show_bug.cgi?id=121561
>> 
>> 
>>  There's also a spreadsheet with some basic tests.

I haven't been able to look at the boost implementation. They do have some
tests but from the implementation description we could improve our testing..
I will probably look at that next year :).

>>>  Would want to compare expected group actual and old to new.
>>> 
>>>  Would want to devise test cases against both common and edge cases.
>>> 
>>>  Also curios about time impact, does it take more time or less.
>>> 
> 
> Yes, the needed calculation time is critical. There are some places in 
> the code, where I had stopped a loop at a fixed count, so that the 
> calculation time is not too long.
>

To be honest, computers are so fast these days that I think most people
may sacrifice some performance in exchange for accuracy.

>> 
>> 
>>  The differences are insignificant comparing FreeBSD amd64 (with boost)
>>  vs a VM running Windows XP with Symphony, but I am sure someone
>>  can come up with more creative tests :).
> 
> For accuracy you need a comparison to a value which is calculated 
> without the restriction to data type double. For single values Wolfram 
> Alpha might work, for a larger set of test cases a computer algebra 
> system might be appropriate.
> 

That's a good idea, thanks!

While in Germany I actually met someone from REDUCE, I 'll have to get
back to that.


cheers,

Pedro.

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