diff --git a/math.jl b/math.jl
index 331af70..96b6e7d 100644
--- a/math.jl
+++ b/math.jl
@@ -1,4 +1,5 @@
 using SpecialFunctions
+include("helper.jl")
 
 # Gaussian potentials in HO space
 inv_factorial(n) = Iterators.prod(inv.(1:n))