Add GaussianTransiogram

src/GeoStatsFunctions.jl

@@ -98,6 +98,7 @@ export
   # theoretical transiograms
   Transiogram,
   LinearTransiogram,
+  GaussianTransiogram,
   SphericalTransiogram,
   ExponentialTransiogram,
   MatrixExponentialTransiogram,

src/theoretical/transiogram.jl

@@ -25,6 +25,7 @@ isstationary(::Type{<:Transiogram}) = true
 # ----------------
 
 include("transiogram/linear.jl")
+include("transiogram/gaussian.jl")
 include("transiogram/spherical.jl")
 include("transiogram/exponential.jl")
 include("transiogram/matrixexponential.jl")

src/theoretical/transiogram/exponential.jl

@@ -6,7 +6,7 @@
     ExponentialTransiogram(; ranges, proportions)
     ExponentialTransiogram(ball; proportions)
 
-A spherical transiogram with `ranges`, and `proportions`.
+A exponential transiogram with `ranges`, and `proportions`.
 Optionally, use a custom metric `ball`.
 """
 struct ExponentialTransiogram{P,B} <: Transiogram

src/theoretical/transiogram/gaussian.jl

@@ -0,0 +1,32 @@
+# ------------------------------------------------------------------
+# Licensed under the MIT License. See LICENSE in the project root.
+# ------------------------------------------------------------------
+
+"""
+    GaussianTransiogram(; ranges, proportions)
+    GaussianTransiogram(ball; proportions)
+
+A Gaussian transiogram with `ranges`, and `proportions`.
+Optionally, use a custom metric `ball`.
+"""
+struct GaussianTransiogram{P,B} <: Transiogram
+  prop::P
+  ball::B
+end
+
+GaussianTransiogram(ball; proportions=(0.5, 0.5)) = GaussianTransiogram(proportions, ball)
+
+GaussianTransiogram(; ranges=(1.0u"m", 1.0u"m"), proportions=(0.5, 0.5)) =
+  GaussianTransiogram(proportions, MetricBall(ranges))
+
+constructor(::GaussianTransiogram) = GaussianTransiogram
+
+function (t::GaussianTransiogram)(h)
+  r = radius(t.ball)
+  p = t.prop
+  L = length(p)
+  h′, r′ = unitless(h, r)
+  v = 1 - exp(-3(h′ / r′)^2)
+  T = typeof(p[1] * v)
+  SMatrix{L,L}(i == j ? T(1 - (1 - p[j]) * v) : T((p[j] * v)) for i in 1:L, j in 1:L)
+end