[R] Mean calculated from R1.9.1 different from R2.0.1

[Petr Pikal]

Hi

Isn't it due to rounding and floating point precision of different 
OSses?

Cheers
Petr



On 10 Feb 2005 at 3:44, Chang-Heok Soh wrote:

> Hello,
> I ran my simulations on the Unix verson of R1.9.1 and the Windows
> version of R2.0.1 on XP.  I kept getting different values for the mean
> of the same column of the same matrix, and am perplexed.  I would
> appreciate if anyone could help explain the difference?
> 
> Here is a sample code:
> 
> set.seed(7293)
> z1v <- rnorm(1000, mean=68, sd=13)
> z1v <- (z1v-mean(z1v))/sd(z1v)
> 
> Using R1.9.1 on Unix, I get:
> 
> mean(z1v)
> [1] -4.88775e-15
> 
> Using R2.0.1 on Windows XP, I get:
> 
> mean(z1v)
> [1] -3.7497e-16
> 
> The same problem occurs when I dump the data from one version and then
> source it using the other version.
> 
> Thanks for the help.
> 
> Regards,
> Chang-Heok
> 
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Petr Pikal
petr.pikal at precheza.cz