Add coefficient_ring for series rings

Author: SoongNoonien

src/RelSeries.jl

@@ -29,6 +29,10 @@ base_ring_type(::Type{<:SeriesRing{T}}) where T <: RingElement = parent_type(T)
 
 base_ring(R::SeriesRing{T}) where T <: RingElement = R.base_ring::parent_type(T)
 
+coefficient_ring_type(T::Type{<:SeriesRing}) = base_ring_type(T)
+
+coefficient_ring(R::SeriesRing) = base_ring(R)
+
 function is_domain_type(::Type{T}) where {S <: RingElement, T <: SeriesElem{S}}
    return is_domain_type(S)
 end

src/generic/LaurentSeries.jl

@@ -41,6 +41,14 @@ base_ring(R::LaurentSeriesRing{T}) where T <: RingElement = R.base_ring::parent_
 
 base_ring(R::LaurentSeriesField{T}) where T <: FieldElement = R.base_ring::parent_type(T)
 
+coefficient_ring_type(T::Type{<:LaurentSeriesRing}) = base_ring_type(T)
+
+coefficient_ring_type(T::Type{<:LaurentSeriesField}) = base_ring_type(T)
+
+coefficient_ring(R::LaurentSeriesRing) = coefficient_ring(R)
+
+coefficient_ring(R::LaurentSeriesField) = coefficient_ring(R)
+
 function is_domain_type(::Type{T}) where {S <: RingElement, T <: LaurentSeriesElem{S}}
    return is_domain_type(S)
 end

src/generic/PuiseuxSeries.jl

@@ -57,6 +57,14 @@ base_ring(R::PuiseuxSeriesRing{T}) where T <: RingElement = base_ring(laurent_ri
 
 base_ring(R::PuiseuxSeriesField{T}) where T <: FieldElement = base_ring(laurent_ring(R))
 
+coefficient_ring_type(T::Type{<:PuiseuxSeriesRing}) = base_ring_type(T)
+
+coefficient_ring_type(T::Type{<:PuiseuxSeriesField}) = base_ring_type(T)
+
+coefficient_ring(R::PuiseuxSeriesRing) = coefficient_ring(R)
+
+coefficient_ring(R::PuiseuxSeriesField) = coefficient_ring(R)
+
 @doc raw"""
     max_precision(R::PuiseuxSeriesRing{T}) where T <: RingElement
 

test/generic/LaurentSeries-test.jl

@@ -40,10 +40,16 @@ end
    @test elem_type(Generic.LaurentSeriesRing{elem_type(S)}) == Generic.LaurentSeriesRingElem{elem_type(S)}
    @test parent_type(Generic.LaurentSeriesRingElem{elem_type(S)}) == Generic.LaurentSeriesRing{elem_type(S)}
 
+   @test coefficient_ring(T) == S
+   @test coefficient_ring_type(T) == typeof(coefficient_ring(T))
+
    @test elem_type(U) == Generic.LaurentSeriesFieldElem{Rational{BigInt}}
    @test elem_type(Generic.LaurentSeriesField{Rational{BigInt}}) == Generic.LaurentSeriesFieldElem{Rational{BigInt}}
    @test parent_type(Generic.LaurentSeriesFieldElem{Rational{BigInt}}) == Generic.LaurentSeriesField{Rational{BigInt}}
 
+   @test coefficient_ring(U) === QQ
+   @test coefficient_ring_type(U) == typeof(coefficient_ring(U))
+
    @test isa(R, Generic.LaurentSeriesRing)
    @test isa(T, Generic.LaurentSeriesRing)
    @test isa(U, Generic.LaurentSeriesField)

test/generic/PuiseuxSeries-test.jl

@@ -42,10 +42,16 @@ end
    @test elem_type(Generic.PuiseuxSeriesRing{elem_type(S)}) == Generic.PuiseuxSeriesRingElem{elem_type(S)}
    @test parent_type(Generic.PuiseuxSeriesRingElem{elem_type(S)}) == Generic.PuiseuxSeriesRing{elem_type(S)}
 
+   @test coefficient_ring(T) == S
+   @test coefficient_ring_type(T) == typeof(coefficient_ring(T))
+
    @test elem_type(U) == Generic.PuiseuxSeriesFieldElem{Rational{BigInt}}
    @test elem_type(Generic.PuiseuxSeriesField{Rational{BigInt}}) == Generic.PuiseuxSeriesFieldElem{Rational{BigInt}}
    @test parent_type(Generic.PuiseuxSeriesFieldElem{Rational{BigInt}}) == Generic.PuiseuxSeriesField{Rational{BigInt}}
 
+   @test coefficient_ring(U) === QQ
+   @test coefficient_ring_type(U) == typeof(coefficient_ring(U))
+
    @test isa(R, Generic.PuiseuxSeriesRing)
    @test isa(T, Generic.PuiseuxSeriesRing)
    @test isa(U, Generic.PuiseuxSeriesField)

test/generic/RelSeries-test.jl

@@ -45,10 +45,16 @@ end
    @test elem_type(Generic.RelPowerSeriesRing{BigInt}) == Generic.RelSeries{BigInt}
    @test parent_type(Generic.RelSeries{BigInt}) == Generic.RelPowerSeriesRing{BigInt}
 
+   @test coefficient_ring(R) === ZZ
+   @test coefficient_ring_type(R) == typeof(coefficient_ring(R))
+
    @test elem_type(T) == Generic.RelSeries{elem_type(S)}
    @test elem_type(Generic.RelPowerSeriesRing{elem_type(S)}) == Generic.RelSeries{elem_type(S)}
    @test parent_type(Generic.RelSeries{elem_type(S)}) == Generic.RelPowerSeriesRing{elem_type(S)}
 
+   @test coefficient_ring(T) == S
+   @test coefficient_ring_type(T) == typeof(coefficient_ring(T))
+
    @test isa(R, Generic.RelPowerSeriesRing)
 
    @test isa(T, Generic.RelPowerSeriesRing)