diff --git a/src/variogram/circular.jl b/src/variogram/circular.jl
index 8956d83..9b0ab5d 100644
--- a/src/variogram/circular.jl
+++ b/src/variogram/circular.jl
@@ -15,6 +15,10 @@ CircularVariogram(ball; sill=1.0, nugget=zero(typeof(sill))) = CircularVariogram
 
 CircularVariogram(; range=1.0, sill=1.0, nugget=zero(typeof(sill))) = CircularVariogram(sill, nugget, MetricBall(range))
 
+variotype(::CircularVariogram) = CircularVariogram
+
+isstationary(::Type{<:CircularVariogram}) = true
+
 function (γ::CircularVariogram)(h)
   r = radius(γ.ball)
   s = γ.sill
@@ -22,7 +26,3 @@ function (γ::CircularVariogram)(h)
   v = h ≤ r ? 1 - (2 / π) * acos(h / r) + (2h / (π * r)) * sqrt(1 - (h^2 / r^2)) : one(h)
   (s - n) * v + (h > zero(h)) * n
 end
-
-variotype(::CircularVariogram) = CircularVariogram
-
-isstationary(::Type{<:CircularVariogram}) = true
diff --git a/src/variogram/cubic.jl b/src/variogram/cubic.jl
index 15f5483..06e8421 100644
--- a/src/variogram/cubic.jl
+++ b/src/variogram/cubic.jl
@@ -19,6 +19,10 @@ CubicVariogram(ball; sill=1.0, nugget=zero(typeof(sill))) = CubicVariogram(sill,
 
 CubicVariogram(; range=1.0, sill=1.0, nugget=zero(typeof(sill))) = CubicVariogram(sill, nugget, MetricBall(range))
 
+variotype(::CubicVariogram) = CubicVariogram
+
+isstationary(::Type{<:CubicVariogram}) = true
+
 function (γ::CubicVariogram)(h::T) where {T}
   r = radius(γ.ball)
   s = γ.sill
@@ -33,7 +37,3 @@ function (γ::CubicVariogram)(h::T) where {T}
 
   (h < r) * (s - n) * s1 + (h ≥ r) * (s - n) * s2 + (h > 0) * n
 end
-
-variotype(::CubicVariogram) = CubicVariogram
-
-isstationary(::Type{<:CubicVariogram}) = true
diff --git a/src/variogram/exponential.jl b/src/variogram/exponential.jl
index 4f07718..ec57bba 100644
--- a/src/variogram/exponential.jl
+++ b/src/variogram/exponential.jl
@@ -20,13 +20,13 @@ ExponentialVariogram(ball; sill=1.0, nugget=zero(typeof(sill))) = ExponentialVar
 ExponentialVariogram(; range=1.0, sill=1.0, nugget=zero(typeof(sill))) =
   ExponentialVariogram(sill, nugget, MetricBall(range))
 
+variotype(::ExponentialVariogram) = ExponentialVariogram
+
+isstationary(::Type{<:ExponentialVariogram}) = true
+
 function (γ::ExponentialVariogram)(h)
   r = radius(γ.ball)
   s = γ.sill
   n = γ.nugget
   (s - n) * (1 - exp(-3(h / r))) + (h > 0) * n
 end
-
-variotype(::ExponentialVariogram) = ExponentialVariogram
-
-isstationary(::Type{<:ExponentialVariogram}) = true
diff --git a/src/variogram/gaussian.jl b/src/variogram/gaussian.jl
index 1eb5edf..2d1c110 100644
--- a/src/variogram/gaussian.jl
+++ b/src/variogram/gaussian.jl
@@ -19,6 +19,10 @@ GaussianVariogram(ball; sill=1.0, nugget=zero(typeof(sill))) = GaussianVariogram
 
 GaussianVariogram(; range=1.0, sill=1.0, nugget=zero(typeof(sill))) = GaussianVariogram(sill, nugget, MetricBall(range))
 
+variotype(::GaussianVariogram) = GaussianVariogram
+
+isstationary(::Type{<:GaussianVariogram}) = true
+
 function (γ::GaussianVariogram)(h)
   # add small eps to nugget
   # for numerical stability
@@ -27,7 +31,3 @@ function (γ::GaussianVariogram)(h)
   n = γ.nugget + typeof(s)(1e-6)
   (s - n) * (1 - exp(-3(h / r)^2)) + (h > 0) * n
 end
-
-variotype(::GaussianVariogram) = GaussianVariogram
-
-isstationary(::Type{<:GaussianVariogram}) = true
diff --git a/src/variogram/matern.jl b/src/variogram/matern.jl
index 86cdf3e..7ddf81c 100644
--- a/src/variogram/matern.jl
+++ b/src/variogram/matern.jl
@@ -22,6 +22,10 @@ MaternVariogram(ball; sill=1.0, nugget=zero(typeof(sill)), order=1.0) = MaternVa
 MaternVariogram(; range=1.0, sill=1.0, nugget=zero(typeof(sill)), order=1.0) =
   MaternVariogram(sill, nugget, order, MetricBall(range))
 
+variotype(::MaternVariogram) = MaternVariogram
+
+isstationary(::Type{<:MaternVariogram}) = true
+
 function (γ::MaternVariogram)(h::T) where {T}
   r = radius(γ.ball)
   s = γ.sill
@@ -38,7 +42,3 @@ function (γ::MaternVariogram)(h::T) where {T}
 
   (s - n) * (1 - 2^(1 - ν) / Γ * δ^ν * Β) + (h > 0) * n
 end
-
-variotype(::MaternVariogram) = MaternVariogram
-
-isstationary(::Type{<:MaternVariogram}) = true
diff --git a/src/variogram/nugget.jl b/src/variogram/nugget.jl
index 8d934e4..6e3bbba 100644
--- a/src/variogram/nugget.jl
+++ b/src/variogram/nugget.jl
@@ -13,16 +13,16 @@ end
 
 NuggetEffect(; nugget=1.0) = NuggetEffect(nugget)
 
-(γ::NuggetEffect)(h) = (h > 0) * γ.nugget
+variotype(::NuggetEffect) = NuggetEffect
 
-(γ::NuggetEffect)(u::Point, v::Point) = ifelse(u == v, zero(γ.nugget), γ.nugget)
+isstationary(::Type{<:NuggetEffect}) = true
 
-Base.range(::NuggetEffect{T}) where {T} = zero(T)
+isisotropic(::NuggetEffect) = true
 
 sill(γ::NuggetEffect) = γ.nugget
 
-variotype(::NuggetEffect) = NuggetEffect
+Base.range(::NuggetEffect{T}) where {T} = zero(T)
 
-isstationary(::Type{<:NuggetEffect}) = true
+(γ::NuggetEffect)(h) = (h > 0) * γ.nugget
 
-isisotropic(::NuggetEffect) = true
+(γ::NuggetEffect)(u::Point, v::Point) = ifelse(u == v, zero(γ.nugget), γ.nugget)
diff --git a/src/variogram/pentaspherical.jl b/src/variogram/pentaspherical.jl
index 5b817a0..a423a57 100644
--- a/src/variogram/pentaspherical.jl
+++ b/src/variogram/pentaspherical.jl
@@ -20,6 +20,10 @@ PentasphericalVariogram(ball; sill=1.0, nugget=zero(typeof(sill))) = Pentaspheri
 PentasphericalVariogram(; range=1.0, sill=1.0, nugget=zero(typeof(sill))) =
   PentasphericalVariogram(sill, nugget, MetricBall(range))
 
+variotype(::PentasphericalVariogram) = PentasphericalVariogram
+
+isstationary(::Type{<:PentasphericalVariogram}) = true
+
 function (γ::PentasphericalVariogram)(h::T) where {T}
   r = radius(γ.ball)
   s = γ.sill
@@ -34,7 +38,3 @@ function (γ::PentasphericalVariogram)(h::T) where {T}
 
   (h < r) * (s - n) * s1 + (h ≥ r) * (s - n) * s2 + (h > 0) * n
 end
-
-variotype(::PentasphericalVariogram) = PentasphericalVariogram
-
-isstationary(::Type{<:PentasphericalVariogram}) = true
diff --git a/src/variogram/power.jl b/src/variogram/power.jl
index b976193..3ff349e 100644
--- a/src/variogram/power.jl
+++ b/src/variogram/power.jl
@@ -15,6 +15,12 @@ end
 
 PowerVariogram(; scaling=1.0, nugget=zero(typeof(scaling)), exponent=1.0) = PowerVariogram(scaling, nugget, exponent)
 
+variotype(::PowerVariogram) = PowerVariogram
+
+isstationary(::Type{<:PowerVariogram}) = false
+
+isisotropic(::PowerVariogram) = true
+
 function (γ::PowerVariogram)(h)
   s = γ.scaling
   a = γ.exponent
@@ -29,9 +35,3 @@ function (γ::PowerVariogram)(u::Point, v::Point)
   h = evaluate(d, x, y)
   γ(h)
 end
-
-variotype(::PowerVariogram) = PowerVariogram
-
-isstationary(::Type{<:PowerVariogram}) = false
-
-isisotropic(::PowerVariogram) = true
diff --git a/src/variogram/sinehole.jl b/src/variogram/sinehole.jl
index 1faf9fa..5664abe 100644
--- a/src/variogram/sinehole.jl
+++ b/src/variogram/sinehole.jl
@@ -19,6 +19,10 @@ SineHoleVariogram(ball; sill=1.0, nugget=zero(typeof(sill))) = SineHoleVariogram
 
 SineHoleVariogram(; range=1.0, sill=1.0, nugget=zero(typeof(sill))) = SineHoleVariogram(sill, nugget, MetricBall(range))
 
+variotype(::SineHoleVariogram) = SineHoleVariogram
+
+isstationary(::Type{<:SineHoleVariogram}) = true
+
 function (γ::SineHoleVariogram)(h::T) where {T}
   r = radius(γ.ball)
   s = γ.sill
@@ -31,7 +35,3 @@ function (γ::SineHoleVariogram)(h::T) where {T}
 
   (s - n) * (1 - sin(c * h′ / r) / (c * h′ / r)) + (h′ > 0) * n
 end
-
-variotype(::SineHoleVariogram) = SineHoleVariogram
-
-isstationary(::Type{<:SineHoleVariogram}) = true
diff --git a/src/variogram/spherical.jl b/src/variogram/spherical.jl
index ba3a999..b7bbdd4 100644
--- a/src/variogram/spherical.jl
+++ b/src/variogram/spherical.jl
@@ -20,6 +20,10 @@ SphericalVariogram(ball; sill=1.0, nugget=zero(typeof(sill))) = SphericalVariogr
 SphericalVariogram(; range=1.0, sill=1.0, nugget=zero(typeof(sill))) =
   SphericalVariogram(sill, nugget, MetricBall(range))
 
+variotype(::SphericalVariogram) = SphericalVariogram
+
+isstationary(::Type{<:SphericalVariogram}) = true
+
 function (γ::SphericalVariogram)(h::T) where {T}
   r = radius(γ.ball)
   s = γ.sill
@@ -33,7 +37,3 @@ function (γ::SphericalVariogram)(h::T) where {T}
 
   (h < r) * (s - n) * s1 + (h ≥ r) * (s - n) * s2 + (h > 0) * n
 end
-
-variotype(::SphericalVariogram) = SphericalVariogram
-
-isstationary(::Type{<:SphericalVariogram}) = true