Merge pull request #244 from araujoms/main

refactor inv to remove duplicated code

Author: JeffreySarnoff

src/DoubleFloats.jl

@@ -85,7 +85,6 @@ include("Double.jl")   # Double64, Double32, Double16
 include("math/errorfree.jl")
 include("math/leasterror.jl")
 
-include("doubletriple/double.jl")
 include("doubletriple/double_consts.jl")
 include("doubletriple/triple.jl")
 include("doubletriple/triple_consts.jl")

src/doubletriple/double.jl

@@ -1,5 +1,14 @@
-function inv_dd_dd(x::Tuple{T,T}) where {T<:IEEEFloat}
-    return DWInvDW3(HI(x), LO(x))
+# inv using Algorithms 17 and 18 from Tight and rigorous error bounds
+
+function inv_dd_dd(y::Tuple{T, T}) where {T<:IEEEFloat}
+   yₕᵢ, yₗₒ = y
+   tₕᵢ = inv(yₕᵢ)
+   rₕᵢ = fma(yₕᵢ, -tₕᵢ, one(T))
+   rₗₒ = -(yₗₒ * tₕᵢ)
+   eₕᵢ, eₗₒ = two_hilo_sum(rₕᵢ, rₗₒ)
+   dₕᵢ, dₗₒ = mul_ddfp_dd((eₕᵢ, eₗₒ), tₕᵢ)
+   zₕᵢ, zₗₒ = add_ddfp_dd((dₕᵢ, dₗₒ), tₕᵢ)
+   return zₕᵢ, zₗₒ
 end
 
 @inline function square_dd_dd(a::Tuple{T,T}) where {T<:IEEEFloat}

src/math/ops/op_dd_dd.jl

@@ -10,16 +10,6 @@ end
     return hi, lo
 end
 
-#=
-@inline function mul_ddfp_dd(x::Tuple{T,T}, y::T) where {T<:IEEEFloat}
-    hi, lo = x
-    hihi, hilo = two_prod(y, hi)
-    lohi, lolo = two_prod(y, lo)
-    hi, lo = two_sum(hihi, hilo, lohi, lolo)
-    return hi, lo
-end
-=#
-
 # Algorithm 12 from Tight and rigourous error bounds.  relative error <= 5u²
 @inline function mul_ddfp_dd(x::Tuple{T,T}, y::T) where T<:IEEEFloat
     xhi, xlo = x