R version 3.2.2 (2015-08-14) -- "Fire Safety"
Copyright (C) 2015 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

> library(sp)
> data(meuse)
> library(gstat)
> v=variogram(log(zinc)~1,~x+y,meuse,cutoff=500,wi=100)
> v$gamma=c(0.5,1,2,3,3)
> fit.variogram(v, vgm(1, "Sph", 300, 0),warn.if.neg=TRUE)
  model    psill   range
1   Nug 0.000000    0.00
2   Sph 7.878195 1567.77
Warning message:
In fit.variogram(v, vgm(1, "Sph", 300, 0), warn.if.neg = TRUE) :
  partial sill or nugget fixed at zero value
> fit.variogram(v, vgm(1, "Sph", 300, 0),warn.if.neg=FALSE)
  model    psill   range
1   Nug 0.000000    0.00
2   Sph 7.878195 1567.77
> 
> proc.time()
   user  system elapsed 
  0.708   0.244   0.718