R version 2.15.2 (2012-10-26) -- "Trick or Treat"
Copyright (C) 2012 The R Foundation for Statistical Computing
ISBN 3-900051-07-0
Platform: x86_64-pc-linux-gnu (64-bit)

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> set.seed(1131)
> d = data.frame(x=runif(50),y=runif(50),z=runif(50),v=rnorm(50))
> library(gstat)
Loading required package: sp
> xx = krige.cv(v~1,~x+y+z,d,model=vgm(1,"Exp",1), verbose=F, set=list(debug=0))
> summary(xx)
   var1.pred          var1.var         observed          residual       
 Min.   :-1.1633   Min.   :0.1163   Min.   :-2.2396   Min.   :-2.17554  
 1st Qu.:-0.5713   1st Qu.:0.1748   1st Qu.:-0.8760   1st Qu.:-0.78811  
 Median :-0.2006   Median :0.1921   Median :-0.2194   Median : 0.11750  
 Mean   :-0.1651   Mean   :0.2079   Mean   :-0.1418   Mean   : 0.02327  
 3rd Qu.: 0.1614   3rd Qu.:0.2396   3rd Qu.: 0.5005   3rd Qu.: 0.85076  
 Max.   : 1.0846   Max.   :0.4257   Max.   : 1.8566   Max.   : 2.52242  
     zscore             fold             x                  y           
 Min.   :-5.1678   Min.   : 1.00   Min.   :0.006784   Min.   :0.003404  
 1st Qu.:-1.8749   1st Qu.:13.25   1st Qu.:0.239662   1st Qu.:0.246573  
 Median : 0.2453   Median :25.50   Median :0.486683   Median :0.452500  
 Mean   : 0.0167   Mean   :25.50   Mean   :0.499664   Mean   :0.496887  
 3rd Qu.: 2.0201   3rd Qu.:37.75   3rd Qu.:0.747297   3rd Qu.:0.739427  
 Max.   : 7.3541   Max.   :50.00   Max.   :0.987538   Max.   :0.987169  
       z           
 Min.   :0.001641  
 1st Qu.:0.186459  
 Median :0.448503  
 Mean   :0.471422  
 3rd Qu.:0.724035  
 Max.   :0.994198  
> 
> proc.time()
   user  system elapsed 
  0.852   0.056   0.891