diff --git a/ext/SymEngineTermInterfaceExt.jl b/ext/SymEngineTermInterfaceExt.jl
index 942a08e..b4c2749 100644
--- a/ext/SymEngineTermInterfaceExt.jl
+++ b/ext/SymEngineTermInterfaceExt.jl
@@ -1,7 +1,6 @@
 module SymEngineTermInterfaceExt
 
 import SymEngine
-import SymEngine: SymbolicType
 import TermInterface
 
 
@@ -22,7 +21,27 @@ import TermInterface
 λ(::Val{:Csch}) = csch; λ(::Val{:Sech}) = sech; λ(::Val{:Coth}) = coth
 λ(::Val{:Asinh}) = asinh; λ(::Val{:Acosh}) = acosh; λ(::Val{:Atanh}) = atanh
 λ(::Val{:Acsch}) = acsch; λ(::Val{:Asech}) = asech; λ(::Val{:Acoth}) = acoth
-λ(::Val{:Gamma}) = gamma; λ(::Val{:Zeta}) = zeta; λ(::Val{:LambertW}) = lambertw
+λ(::Val{:ATan2}) = atan;
+λ(::Val{:Beta}) = SymEngine.SpecialFunctions.beta;
+λ(::Val{:Gamma}) = SymEngine.SpecialFunctions.gamma;
+λ(::Val{:PolyGamma}) = SymEngine.SpecialFunctions.polygamma;
+λ(::Val{:LogGamma}) = SymEngine.SpecialFunctions.loggamma;
+λ(::Val{:Erf}) = SymEngine.SpecialFunctions.erf;
+λ(::Val{:Erfc}) = SymEngine.SpecialFunctions.erfc;
+λ(::Val{:Zeta}) = SymEngine.SpecialFunctions.zeta;
+λ(::Val{:LambertW}) = SymEngine.SpecialFunctions.lambertw
+
+
+
+const julia_operations = Vector{Any}(missing, length(SymEngine.symengine_classes))
+for (i,s) ∈ enumerate(SymEngine.symengine_classes)
+    val = try
+        λ(Val(s))
+    catch err
+        missing
+    end
+    julia_operations[i] = val
+end
 
 #==
 Check if x represents an expression tree. If returns true, it will be assumed that operation(::T) and arguments(::T) methods are defined. Definining these three should allow use of SymbolicUtils.simplify on custom types. Optionally symtype(x) can be defined to return the expected type of the symbolic expression.
@@ -40,7 +59,7 @@ TermInterface.isexpr(x::SymEngine.SymbolicType) = TermInterface.iscall(x)
 
 function TermInterface.operation(x::SymEngine.SymbolicType)
     TermInterface.iscall(x) || error("$(typeof(x)) doesn't have an operation!")
-    return λ(x)
+    return julia_operations[SymEngine.get_type(x) + 1]
 end
 
 function TermInterface.arguments(x::SymEngine.SymbolicType)
diff --git a/src/mathfuns.jl b/src/mathfuns.jl
index 8139129..81d074b 100644
--- a/src/mathfuns.jl
+++ b/src/mathfuns.jl
@@ -51,19 +51,42 @@ for (meth, libnm, modu) in [
                       (:acsch,:acsch,:Base),
                       (:atanh,:atanh,:Base),
                       (:acoth,:acoth,:Base),
-                      (:gamma,:gamma,:SpecialFunctions),
                       (:log,:log,:Base),
                       (:sqrt,:sqrt,:Base),
                       (:exp,:exp,:Base),
                       (:sign, :sign, :Base),
-                      (:eta,:dirichlet_eta,:SpecialFunctions),
-                      (:zeta,:zeta,:SpecialFunctions),
+                      (:ceil, :ceiling, :Base),
+                      (:floor, :floor, :Base)
                       ]
     eval(:(import $modu.$meth))
     IMPLEMENT_ONE_ARG_FUNC(:($modu.$meth), libnm)
 end
+
+for (meth, libnm, modu) in [
+    (:gamma,:gamma,:SpecialFunctions),
+    (:loggamma,:loggamma,:SpecialFunctions),
+    (:eta,:dirichlet_eta,:SpecialFunctions),
+    (:zeta,:zeta,:SpecialFunctions),
+    (:erf, :erf, :SpecialFunctions),
+    (:erfc, :erfc, :SpecialFunctions)
+]
+    eval(:(import $modu.$meth))
+    IMPLEMENT_ONE_ARG_FUNC(:($modu.$meth), libnm)
+end
+
+for (meth, libnm, modu) in [
+    (:beta, :beta, :SpecialFunctions),
+    (:polygamma, :polygamma, :SpecialFunctions),
+    (:loggamma,:loggamma,:SpecialFunctions),
+    ]
+    eval(:(import $modu.$meth))
+    IMPLEMENT_TWO_ARG_FUNC(:($modu.$meth), libnm)
+end
+
 Base.abs2(x::SymEngine.Basic) = abs(x)^2
 
+
+
 if get_symbol(:basic_atan2) != C_NULL
     import Base.atan
     IMPLEMENT_TWO_ARG_FUNC(:(Base.atan), :atan2)
diff --git a/src/numerics.jl b/src/numerics.jl
index c0b80d1..017ade1 100644
--- a/src/numerics.jl
+++ b/src/numerics.jl
@@ -262,12 +262,6 @@ end
 trunc(x::Basic, args...) = Basic(trunc(N(x), args...))
 trunc(::Type{T},x::Basic, args...) where {T <: Integer} = convert(T, trunc(x,args...))
 
-ceil(x::Basic) = Basic(ceil(N(x)))
-ceil(::Type{T},x::Basic) where {T <: Integer} = convert(T, ceil(x))
-
-floor(x::Basic) = Basic(floor(N(x)))
-floor(::Type{T},x::Basic) where {T <: Integer} = convert(T, floor(x))
-
 round(x::Basic; kwargs...) = Basic(round(N(x); kwargs...))
 round(::Type{T},x::Basic; kwargs...) where {T <: Integer} = convert(T, round(x; kwargs...))
 
diff --git a/src/subs.jl b/src/subs.jl
index 5f5b9e4..9e23f8a 100644
--- a/src/subs.jl
+++ b/src/subs.jl
@@ -62,18 +62,22 @@ fn_map = Dict(
 
 map_fn(key, fn_map) = haskey(fn_map, key) ? fn_map[key] : Symbol(lowercase(string(key)))
 
+const julia_classes = map_fn.(symengine_classes, (fn_map,))
+get_julia_class(x::Basic) = julia_classes[get_type(x) + 1]
+Base.nameof(ex::Basic) = Symbol(toString(ex))
+
 function _convert(::Type{Expr}, ex::Basic)
     fn = get_symengine_class(ex)
 
     if fn == :Symbol
-        return Symbol(toString(ex))
+        return nameof(ex)
     elseif (fn in number_types) || (fn == :Constant)
         return N(ex)
     end
 
     as = get_args(ex)
-
-    Expr(:call, map_fn(fn, fn_map), [_convert(Expr,a) for a in as]...)
+    fn′ = get_julia_class(ex)
+    Expr(:call, fn′, [_convert(Expr,a) for a in as]...)
 end
 
 
@@ -81,7 +85,7 @@ function convert(::Type{Expr}, ex::Basic)
     fn = get_symengine_class(ex)
 
     if fn == :Symbol
-        return Expr(:call, :*, Symbol(toString(ex)), 1)
+        return Expr(:call, :*, nameof(ex), 1)
     elseif (fn in number_types) || (fn == :Constant)
         return Expr(:call, :*, N(ex), 1)
     end