Adding convenient promotions

Author: lrnv

src/primitive.jl

@@ -113,6 +113,8 @@ end
     ex = :($ex; TaylorScalar($([Symbol('v', i) for i in 1:N]...)))
     return :(@inbounds $ex)
 end
+@inline *(a::TaylorScalar{T1, N}, b::TaylorScalar{T2, N}) where {T1,T2,N} = *(promote(a,b)...)
+@inline /(a::TaylorScalar{T1, N}, b::TaylorScalar{T2, N}) where {T1,T2,N} = *(promote(a,b)...)
 
 for R in (Integer, Real)
     @eval @generated function ^(t::TaylorScalar{T, N}, n::S) where {S <: $R, T, N}

src/scalar.jl

@@ -89,6 +89,9 @@ function promote_rule(::Type{TaylorScalar{T, N}},
         ::Type{S}) where {T, S, N}
     TaylorScalar{promote_type(T, S), N}
 end
+function promote_rule(::Type{TaylorScalar{T1, N}}, ::Type{TaylorScalar{T2,N}}) where {T1, T2, N}
+TaylorScalar{promote_type(T1,T2), N}
+end
 
 function (::Type{F})(x::TaylorScalar{T, N}) where {T, N, F <: AbstractFloat}
     F(primal(x))