[STATSGRASS] different kriging results with the same parameters

[Carlos "Guâno" Grohmann]

I was kriging some SRTM DEMs, and I noticed that I get different
results with the same parameters!!
 check out:

summary(srtm) - original data
Data attributes:
     band1
 Min.   : 634.0
 1st Qu.: 759.0
 Median : 814.0
 Mean   : 856.5
 3rd Qu.: 923.0
 Max.   :1312.0

vrg.eye<-(vgm(psill=950, model="Gau", range=245, nugget=6.2));

OK_pred_md250 <- krige(srtm$band1 ~ 1, loc=srtm2, newdata=mask_SG,
model=vrg.eye, maxdist=250);


summary(OK_pred_md250);
Data attributes:
   var1.pred         var1.var
 Min.   : 632.8   Min.   :  8.054
 1st Qu.: 759.2   1st Qu.:  8.576
 Median : 814.3   Median :  8.712
 Mean   : 856.4   Mean   :  9.052
 3rd Qu.: 923.6   3rd Qu.:  8.865
 Max.   :1307.6   Max.   :395.609

Data attributes:
   var1.pred         var1.var
 Min.   : 632.4   Min.   :  8.040
 1st Qu.: 759.2   1st Qu.:  8.577
 Median : 814.3   Median :  8.711
 Mean   : 856.4   Mean   :  9.048
 3rd Qu.: 923.6   3rd Qu.:  8.863
 Max.   :1306.2   Max.   :341.567

Data attributes:
   var1.pred         var1.var
 Min.   : 632.9   Min.   :  8.039
 1st Qu.: 759.2   1st Qu.:  8.576
 Median : 814.3   Median :  8.712
 Mean   : 856.4   Mean   :  9.052
 3rd Qu.: 923.6   3rd Qu.:  8.865
 Max.   :1306.9   Max.   :345.084
>


So, the minimum and maximum have changed each time. Why?

thanks

-- 
+-----------------------------------------------------------+
              Carlos Henrique Grohmann - Guano
  Geologist M.Sc  - Doctorate Student at IGc-USP - Brazil
Linux User #89721  - carlos dot grohmann at gmail dot com
+-----------------------------------------------------------+
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