[R] Different results under Windows and Linux

[Kamila Naxerova]

Thanks Bert, I did not describe the problem accurately enough.

Actually, by now, I found out that floating-point imprecision is the 
reason for my confusion. The problem does not arise with the prcomp() 
function but rather with my data preprocessing:

 > means=apply(dev,2,mean,na.rm=T)
 > means
windows 371.19100102494,  432.458908438674   etc.
linux       371.191001024941,432.458908438674   etc.

 > stdev=apply(dev,2,sd,na.rm=T)
 > stdev
windows 872.234567580374, 1324.05572667875   etc.
linux       872.234567580372, 1324.05572667875   etc.

Thanks!
Kamila





Berton Gunter wrote:

>Please provide better documentation to help diagnose the problem. What are
>the PC's ?
>
>-- Bert Gunter
>Genentech Non-Clinical Statistics
>South San Francisco, CA
> 
>"The business of the statistician is to catalyze the scientific learning
>process."  - George E. P. Box
> 
> 
>
>  
>
>>-----Original Message-----
>>From: r-help-bounces at stat.math.ethz.ch 
>>[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Kamila Naxerova
>>Sent: Tuesday, April 18, 2006 3:12 PM
>>To: r-help at stat.math.ethz.ch
>>Subject: [R] Different results under Windows and Linux
>>
>>Hi everyone,
>>
>>disturbingly, a PCA yields different results when I run the analysis 
>>under Windows and Linux.
>>I open the same workspace (which is on an independent partition) and 
>>perform the exact same function (by using the history file). 
>>Interestingly, PC1 is the same, but PC2 comes out totally different.
>>
>>Thanks!
>>Kamila
>>
>>Windows:     
>>platform i386-pc-mingw32
>>arch     i386          
>>os       mingw32       
>>system   i386, mingw32 
>>status                 
>>major    2             
>>minor    2.1           
>>year     2005          
>>month    12            
>>day      20            
>>svn rev  36812         
>>language R       
>>
>>
>>Linux (Suse 10, Kernel 2.6.13-15.8-default)
>>platform i686-pc-linux-gnu
>>arch     i686
>>os       linux-gnu
>>system   i686, linux-gnu
>>status
>>major    2
>>minor    2.1
>>year     2005
>>month    12
>>day      20
>>svn rev  36812
>>language R
>>
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