library(sp)
demo(meuse,ask=FALSE,echo=FALSE)
library(gstat)
v = variogram(log(zinc)~1, meuse, alpha = c(0,45,90,135))
vm = vgm(.25, "Sph", 1000, anis = c(45, 0.5))
plot(v, vm, main = "geometric")
zonal = vgm(.5, "Sph", 1e9, anis = c(45, 1/1e6))
# range is 1e9, effectively infinity, in 45 direction;
# it is 1e9/1e6 = 1000 in 135 direction.
vm = vgm(.25, "Sph", 1000, add.to = zonal)
plot(v, vm, main = "zonal")