diff --git a/src/testing.jl b/src/testing.jl
index 3a4925a0..aa53b820 100644
--- a/src/testing.jl
+++ b/src/testing.jl
@@ -433,21 +433,29 @@ end
 
 # Create a set of random particles with an atomic density simiilar to that
 # of water at room temperature and pressure.
-function xatomic(n=100_000;cutoff=12.,lcell=1)
+function xatomic(n=100_000;cutoff=12.,lcell=1,type=:vec)
     atomic_density_of_water = 0.1 # atoms/ Angstrom^3
     vol = n/atomic_density_of_water
     l = vol^(1/3)
-    x = l*rand(3,n)
+    if type == :mat
+        x = l*rand(3,n)
+    elseif type == :vec
+        x = [ l*rand(SVector{3,Float64}) for _ in 1:n ]
+    end
     box = Box([l,l,l],cutoff,lcell=lcell)
     return x, box
 end
 
 # Create a set of  random particles with the typical density of galaxies
-function xgalactic(n=8_000_000;cutoff=5.,lcell=1)
+function xgalactic(n=8_000_000;cutoff=5.,lcell=1,type=:vec)
     galactic_density = 12 # galaxyes per cubic mega-parsecs (https://doi.org/10.1093/mnras/106.2.121)
     vol = n/galactic_density
     l = vol^(1/3) # mega-parsecs
-    x = l*rand(3,n)
+    if type == :mat
+        x = l*rand(3,n)
+    elseif type == :vec
+        x = [ l*rand(SVector{3,Float64}) for _ in 1:n ]
+    end
     box = Box([l,l,l],cutoff,lcell=lcell)
     return x, box
 end