[Rd] Inconsistent IEEE 754/IEC 60559 rounding behavior (PR#8452)

[Micah_Altman@harvard.edu]

Full_Name: Micah Altman
Version: 2.2
OS: Windows/Linux (RHELv3)
Submission from: (NULL) (71.243.63.53)


Documentation for round()/signif() indicates that  IEC 60559 standard is used, 
"_go to the even digit_" is used for rounding off a 5. However, signif(),
round() and sprintf() do not behave consistently -- rounding using round()
follows this rule, signif() does not, and sprintf() follows the rule on Linux
but not on Windows(): 

> version
         _                      
platform x86_64-redhat-linux-gnu
arch     x86_64                 
os       linux-gnu              
system   x86_64, linux-gnu      
status                          
major    2                      
minor    2.0                    
year     2005                   
month    10                     
day      06                     
svn rev  35749                  
language R                      
> sessionInfo()
R version 2.2.0, 2005-10-06, x86_64-redhat-linux-gnu 

attached base packages:
[1] "methods"   "stats"     "graphics"  "grDevices" "utils"     "datasets" 
[7] "base"    

> sprintf("%#.1g",as.double(0.25))
[1] "0.2"
> round(.25,digits=1)
[1] 0.2
> signif(.25,digits=1)   
[1] 0.3


> version
         _              
platform i386-pc-mingw32
arch     i386           
os       mingw32        
system   i386, mingw32  
status                  
major    2              
minor    2.0            
year     2005           
month    10             
day      06             
svn rev  35749          
language R              
> sessionInfo()
R version 2.2.0, 2005-10-06, i386-pc-mingw32 

attached base packages:
[1] "methods"   "stats"     "graphics"  "grDevices" "utils"     "datasets" 
"base"     
> sprintf("%#.1g",as.double(0.25))
[1] "0.3"
> round(.25,digits=1)
[1] 0.2
> signif(.25,digits=1) 
[1] 0.3
>