fixed eltype for interval (#496)

* fixed eltype for interval

* updated Project.toml

* added test for numtype and eltype

* updated project.toml and added matrix * interval test

* added numtype for interval boxes

Author: lucaferranti

.gitignore

@@ -1 +1,2 @@
 docs/build/
+Manifest.toml

src/IntervalArithmetic.jl

@@ -58,7 +58,7 @@ export
     precedes, strictprecedes, ≼, ≺, ⊂, ⊃, ⊇, contains_zero,
     entireinterval, isentire, nai, isnai, isthin, iscommon, isatomic,
     widen, inf, sup, bisect, mince,
-    parameters, eps, dist,
+    parameters, eps, dist, numtype,
     midpoint_radius, interval_from_midpoint_radius,
     RoundTiesToEven, RoundTiesToAway,
     cancelminus, cancelplus, isunbounded,

src/intervals/arithmetic.jl

@@ -284,15 +284,15 @@ end
 ## Scalar functions on intervals (no directed rounding used)
 
 function mag(a::Interval{T}) where T<:Real
-    isempty(a) && return convert(eltype(a), NaN)
+    isempty(a) && return convert(T, NaN)
     # r1, r2 = setrounding(T, RoundUp) do
     #     abs(a.lo), abs(a.hi)
     # end
     max( abs(a.lo), abs(a.hi) )
 end
 
 function mig(a::Interval{T}) where T<:Real
-    isempty(a) && return convert(eltype(a), NaN)
+    isempty(a) && return convert(T, NaN)
     zero(a.lo) ∈ a && return zero(a.lo)
     r1, r2 = setrounding(T, RoundDown) do
         abs(a.lo), abs(a.hi)
@@ -501,8 +501,8 @@ end
 Return the radius of the `Interval` `a`, such that
 `a ⊆ m ± radius`, where `m = mid(a)` is the midpoint.
 """
-function radius(a::Interval)
-    isempty(a) && return convert(eltype(a), NaN)
+function radius(a::Interval{T}) where {T<:Real}
+    isempty(a) && return convert(T, NaN)
     m = mid(a)
     return max(m - a.lo, a.hi - m)
 end

src/intervals/functions.jl

@@ -19,8 +19,21 @@ end
 Base.literal_pow(::typeof(^), x::Interval{T}, ::Val{p}) where {T,p} = x^p
 
 
-Base.eltype(x::Interval{T}) where {T<:Real} = T
+Base.eltype(x::Interval{T}) where {T<:Real} = Interval{T}
 
+"""
+    numtype(::Interval{T}) where {T<:Real} = T
+
+Returns the type of the bounds of the interval.
+
+### Example
+
+```julia
+julia> numtype(1..2)
+Float64
+```
+"""
+numtype(::Interval{T}) where {T<:Real} = T
 
 
 function ^(a::Interval{BigFloat}, n::Integer)
@@ -359,4 +372,4 @@ end
 function nthroot(a::Interval{T}, n::Integer) where T
     b = nthroot(bigequiv(a), n)
     return convert(Interval{T}, b)
-end 
+end

src/intervals/hyperbolic.jl

@@ -34,7 +34,7 @@ end
 
 
 function acosh(a::Interval{BigFloat})
-    domain = Interval(one(eltype(a)), Inf)
+    domain = Interval(one(BigFloat), Inf)
     a = a ∩ domain
     isempty(a) && return a
 
@@ -43,7 +43,7 @@ end
 
 
 function atanh(a::Interval{BigFloat})
-    domain = Interval(-one(eltype(a)), one(eltype(a)))
+    domain = Interval(-one(BigFloat), one(BigFloat))
     a = a ∩ domain
 
     isempty(a) && return a

src/multidim/intervalbox.jl

@@ -40,7 +40,8 @@ end
 eltype(::Type{IntervalBox{N,T}}) where {N,T} = Interval{T} # Note that this is defined for the type
 
 
-Base.eltype(x::IntervalBox{T}) where {T<:Real} = T
+Base.eltype(x::IntervalBox{N, T}) where {N, T<:Real} = Interval{T}
+numtype(x::IntervalBox{N, T}) where {N, T<:Real} = T
 
 length(X::IntervalBox{N,T}) where {N,T} = N
 
@@ -121,13 +122,13 @@ Splits `x` in `n` intervals in each dimension of the same diameter. These
 intervals are combined in all possible `IntervalBox`-es, which are returned
 as a vector.
 """
-@inline mince(x::IntervalBox{N,T}, n::Int) where {N,T} = 
+@inline mince(x::IntervalBox{N,T}, n::Int) where {N,T} =
     mince(x, ntuple(_ -> n, N))
 
 """
     mince(x::IntervalBox, ncuts::::NTuple{N,Int})
 
-Splits `x[i]` in `ncuts[i]` intervals . These intervals are 
+Splits `x[i]` in `ncuts[i]` intervals . These intervals are
 combined in all possible `IntervalBox`-es, which are returned
 as a vector.
 """

test/interval_tests/construction.jl

@@ -223,6 +223,14 @@ end
     @test typeof(@interval         1 2) == Interval{Float64}
     @test typeof(@interval Float32 1 2) == Interval{Float32}
     @test typeof(@interval Float16 1 2) == Interval{Float16}
+
+    # PR 496
+    @test eltype(Interval(1, 2)) == Interval{Float64}
+    @test numtype(Interval(1, 2)) == Float64
+    @test [1 2; 3 4] * Interval(-1, 1) == [-1..1 -2..2;-3..3 -4..4]
+
+    @test eltype(IntervalBox(1..2, 2..3)) == Interval{Float64}
+    @test numtype(IntervalBox(1..2, 2..3)) == Float64
 end
 
 @testset ".. tests" begin