#822 - Unicode operators

docs/src/lib/approximations.md

@@ -47,6 +47,7 @@ approximate
 ```@docs
 box_approximation
 interval_hull
+□(::LazySet)
 symmetric_interval_hull
 box_approximation_symmetric
 ballinf_approximation

docs/src/lib/interfaces.md

@@ -62,6 +62,7 @@ plot3d!
 ### Globally defined set functions
 
 ```@docs
+○(c, a)
 isconvextype(::Type{<:LazySet})
 low(::LazySet)
 high(::LazySet)
@@ -429,6 +430,7 @@ AbstractHyperrectangle
 This interface defines the following functions:
 
 ```@docs
+□(c, r)
 norm(::AbstractHyperrectangle, ::Real=Inf)
 radius(::AbstractHyperrectangle, ::Real=Inf)
 σ(::AbstractVector, ::AbstractHyperrectangle)

src/Approximations/Approximations.jl

@@ -16,7 +16,7 @@ using LazySets.JuMP: Model, set_silent, @variable, @constraint, optimize!,
                      value, @NLobjective
 
 import Base: convert
-import LazySets: project
+import LazySets: project, □
 
 using ..LazySets: @assert, activate_assertions
 # activate assertions by default

src/Approximations/box_approximation.jl

@@ -78,6 +78,13 @@ Alias for `box_approximation`.
 """
 interval_hull = box_approximation
 
+"""
+    □(X::LazySet)
+
+Alias for `box_approximation(X)`.
+"""
+□(X::LazySet) = box_approximation(X)
+
 # AbstractHyperrectangle specialization
 function box_approximation(S::AbstractHyperrectangle)
     return Hyperrectangle(center(S), radius_hyperrectangle(S))

src/Interfaces/AbstractHyperrectangle.jl

@@ -7,7 +7,8 @@ export AbstractHyperrectangle,
        low, high,
        isflat,
        rectify,
-       volume
+       volume,
+       □
 
 """
     AbstractHyperrectangle{N} <: AbstractZonotope{N}
@@ -46,6 +47,27 @@ julia> subtypes(AbstractHyperrectangle)
 """
 abstract type AbstractHyperrectangle{N} <: AbstractZonotope{N} end
 
+"""
+    □(c, r)
+
+Convenience constructor of `Hyperrectangle`s or `BallInf`s depending on the type
+of `r`.
+
+### Input
+
+- `c` -- center
+- `r` -- radius (either a vector for `Hyperrectangle` or a number for `BallInf`)
+
+### Output
+
+A `Hyperrectangle`s or `BallInf`s depending on the type of `r`.
+
+### Notes
+
+The function symbol can be typed via `\\square[TAB]`.
+"""
+function □(c, r) end
+
 isconvextype(::Type{<:AbstractHyperrectangle}) = true
 
 """

src/Interfaces/LazySet.jl

@@ -40,7 +40,8 @@ export LazySet,
        project,
        rectify,
        permute,
-       chebyshev_center_radius
+       chebyshev_center_radius,
+       ○
 
 """
     LazySet{N}
@@ -162,6 +163,27 @@ Zonotope
 """
 abstract type LazySet{N} end
 
+"""
+    ○(c, a)
+
+Convenience constructor of `Ellipsoid`s or `Ball2`s depending on the type of `a`.
+
+### Input
+
+- `c` -- center
+- `a` -- additional parameter (either a shape matrix for `Ellipsoid` or a radius
+         for `Ball2`)
+
+### Output
+
+A `Ellipsoid`s or `Ball2`s depending on the type of `a`.
+
+### Notes
+
+The function symbol can be typed via `\\bigcirc[TAB]`.
+"""
+function ○(c, a) end
+
 """
     isconvextype(X::Type{<:LazySet})
 

src/Sets/Ball2.jl

@@ -63,6 +63,10 @@ struct Ball2{N<:AbstractFloat, VN<:AbstractVector{N}} <: AbstractCentrallySymmet
     end
 end
 
+function ○(c::VN, r::N) where {N<:AbstractFloat, VN<:AbstractVector{N}}
+    return Ball2(c, r)
+end
+
 isoperationtype(::Type{<:Ball2}) = false
 
 """

src/Sets/BallInf.jl

@@ -55,6 +55,10 @@ struct BallInf{N, VN<:AbstractVector{N}} <: AbstractHyperrectangle{N}
     end
 end
 
+function □(c::VN, r::N) where {N, VN<:AbstractVector{N}}
+    return BallInf(c, r)
+end
+
 isoperationtype(::Type{<:BallInf}) = false
 
 """

src/Sets/Ellipsoid.jl

@@ -114,14 +114,20 @@ struct Ellipsoid{N<:AbstractFloat, VN<:AbstractVector{N},
     end
 end
 
-isoperationtype(::Type{<:Ellipsoid}) = false
-
 # convenience constructor for an ellipsoid centered in the origin
 function Ellipsoid(Q::AbstractMatrix{N}; check_posdef::Bool=true) where {N}
     # TODO: use similar vector type for the center, see #2032
     return Ellipsoid(zeros(N, size(Q, 1)), Q; check_posdef=check_posdef)
 end
 
+function ○(c::VN, shape_matrix::MN) where {N<:AbstractFloat,
+                                           VN<:AbstractVector{N},
+                                           MN<:AbstractMatrix{N}}
+    return Ellipsoid(c, shape_matrix)
+end
+
+isoperationtype(::Type{<:Ellipsoid}) = false
+
 """
     center(E::Ellipsoid)
 

src/Sets/Hyperrectangle.jl

@@ -106,6 +106,10 @@ function Hyperrectangle(; high::AbstractVector,
     return Hyperrectangle(center, radius, check_bounds=check_bounds)
 end
 
+function □(c::VNC, r::VNR) where {N, VNC<:AbstractVector{N}, VNR<:AbstractVector{N}}
+    return Hyperrectangle(c, r)
+end
+
 """
     radius_hyperrectangle(H::Hyperrectangle, i::Int)
 

test/Approximations/box_approximation.jl

@@ -38,6 +38,9 @@ for N in [Float64, Rational{Int}, Float32]
     E = EmptySet{N}(2)
     @test box_approximation(E) == E
 
+    # alias constructors
+    @test interval_hull(b) == □(b) == box_approximation(b)
+
     # ===================================================================
     # Testing box_approximation_symmetric (= symmetric interval hull)
     # ===================================================================

test/Sets/Ball2.jl

@@ -58,6 +58,9 @@ for N in [Float64, Float32]
     d = N[0, -1]
     @test σ(d, b) == N[0, -2]
 
+    # unicode constructor
+    @test ○(center(b), radius(b)) == b
+
     # boundedness
     @test isbounded(b) && isboundedtype(typeof(b))
 

test/Sets/BallInf.jl

@@ -54,6 +54,9 @@ for N in [Float64, Rational{Int}, Float32]
     d = N[1, -1]
     @test σ(d, b) == N[2, -2]
 
+    # unicode constructor
+    @test □(center(b), radius(b)) == b
+
     # center
     c = N[1, 2]
     b = BallInf(c, N(2))

test/Sets/Ellipsoid.jl

@@ -62,6 +62,9 @@ for N in [Float64, Float32]
     d = N[0, -1]
     @test σ(d, E) ≈ N[1, 2 - sqrt(2)]
 
+    # unicode constructor
+    @test ○(center(E), shape_matrix(E)) == E
+
     # boundedness
     @test isbounded(E)
 

test/Sets/Hyperrectangle.jl

@@ -95,6 +95,9 @@ for N in [Float64, Rational{Int}, Float32]
     # diameter
     @test diameter(h) == norm(N[5, 3] - N[1, 1], Inf)
 
+    # unicode constructor
+    @test □(center(h), radius_hyperrectangle(h)) == h
+
     # generators matrix for sparse hyperrectangle
     @test genmat(Hyperrectangle(sparsevec(N[3, 2]), sparsevec(N[2, 1]))) isa SparseMatrixCSC