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From Luc Maisonobe <Luc.Maison...@free.fr>
Subject Re: [math] Re: NormalDistribution
Date Mon, 22 Feb 2010 19:55:06 GMT
Kedar Palsule a écrit :
> Hi Team,
> 
> I cant figure out how to download the development version 2.1 of Apache Math
> Commons.  Alternatively, it would be good if I could figure out how to
> download the nightly build.
> The problem is that the official release, version 2.0, has a bug in a part
> of the code that I need.
> 
> Please let me knowif I can do either

Since 2.1 is not released yet, you have to download the sources from the
subversion repository and build it yourself.

Here is a way to do it from the command line in a linux environment:

 svn checkout http://svn.apache.org/repos/asf/commons/proper/math/trunk
 cd trunk
 mvn package

Luc

> Best Regards,
> Kedar
> 
> On Mon, Feb 22, 2010 at 5:59 AM, kalpa rajadurai <arkalpa@gmail.com> wrote:
> 
>> Hi Team,
>>
>> Thanks for your quick response.
>>
>> We would like to know, when this bug will be fixed and probably when
>> Commons
>> Math 2.1 Version would be released? As our project is dependent on your
>> API,
>> it would be highly appreciated if we get the fix or any kind of work around
>> as soon as possible.
>>
>> Thanks in advance
>>
>> On Sat, Feb 20, 2010 at 8:41 PM, Phil Steitz <phil.steitz@gmail.com>
>> wrote:
>>
>>> kalpa rajadurai wrote:
>>>> Hi Team,
>>>>
>>>> We are working on a small project in designing a web based statistical
>>>> calculator, supporting certain distribution functions.
>>>>
>>>> we used  method *cummulativeProbability(double x)* of *class
>>>> NormalDistributionImpl* for implementing Normal distribution function.
>>>>
>>>> We tried to cross check Apache API's result with that of OpenOffice
>> Calc
>>> and
>>>> Excel's result. In most of the cases, the results matched with each
>>> other.
>>>> But in certain rare cases, the cumulativeProbability() method returned
>> by
>>>> slightly different result when compared to the result returned by
>>> NORMDIST()
>>>> function of openoffice calc and Excel.
>>>>
>>>> Here goes the illustration of the case where we found the mismatch in
>>>> results:
>>>>
>>>> *Using Apache's API:*
>>>> NormalDistribution normDist = new NormalDistributionImpl(40,1.5)
>>>> ;
>>>> try{
>>>> System.out.println("cummulative probability::
>>>> "+normDist.cumulativeProbability(0.908789));
>>>> }
>>>> catch(MathException e){
>>>> e.printStackTrace();
>>>> }
>>>>
>>>> *Result:*
>>>> cummulative probability:: *-8.104628079763643E-15*
>>>>
>>>> *Using openoffice calc:*
>>>> Same input values given in openoffice calc using the formula:
>>>> *=NORMDIST(0.908789;40;1.5;1)*
>>>>
>>>> *Result:*
>>>> *0.0*
>>>>
>>>> *Using Microsoft Excel:*
>>>> Same input values given in excel using the formula:
>>>> *=NORMDIST(0.908789;40;1.5;1)*
>>>>
>>>> *Result:*
>>>> *5.0738E-150*
>>>>
>>>> *Different results:*
>>>> Apache  -8.104628079763643E-15
>>>> Openoffice 0.0
>>>> Excel 5.0738E-150
>>>>
>>>> We wish to know the following things,
>>>> 1.) What is the reason for this variation in results?
>>> The difference is due to different numeric algorithms used to
>>> approximate the cumulative probabilities - in particular how extreme
>>> values are handled.  The probability in the example is very close to
>>> zero - all three agree on that.
>>>
>>>> 2.) Which result is more accurate?
>>> Excel is likely the best answer; though the only confirmation that I
>>> can give of that is that R gives the same answer and the correct
>>> answer is certainly positive.  The worst answer is the one reported
>>> by commons-math.  The value should not be negative.  This is likely
>>> related to an open bug (MATH-301).  Thank you for reporting this.
>>>
>>>> 3.) Is there any possibility to get the same results as Open Office or
>>> Excel
>>>> for this case, using Apache's API?
>>> Commons Math 2.1 will correct the bug mentioned above, so we will
>>> return either 0 or a positive value for this and other extreme tail
>>> probabilities.
>>>
>>> Thanks again for pointing out the discrepancy.
>>>
>>> Phil
>>>
>>>> Hope to receive reply from your team at the earliest as possible.
>>>> Thanks in Advance
>>>>
>>>
>>> ---------------------------------------------------------------------
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>>>
>>>
>>
>> --
>> Karpaga R
>>
>> "Did you always know that?"
>> "No, I didn't. But I believed"
>>  ---Matrix III
>>
> 


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