Define dimension for AbstractScalarSet, add some tests.

Author: tkoolen

src/sets.jl

@@ -7,26 +7,30 @@ Abstract supertype for set objects used to encode constraints.
 """
 abstract type AbstractSet end
 
+"""
+    dimension(s::AbstractSet)
+
+Return the underlying dimension (number of vector components) in the set `s`, i.e.,
+``n`` if the set is a subset of ``\\mathbb{R}^n``.
+"""
+function dimension end
+
 """
     AbstractScalarSet
 
 Abstract supertype for subsets of ``\\mathbb{R}``.
 """
 abstract type AbstractScalarSet <: AbstractSet end
 
+dimension(s::AbstractScalarSet) = 1
+
 """
     AbstractVectorSet
 
 Abstract supertype for subsets of ``\\mathbb{R}^n`` for some ``n``.
 """
 abstract type AbstractVectorSet <: AbstractSet end
 
-"""
-    dimension(s::AbstractVectorSet)
-
-Return the underlying dimension (number of vector components) in the set `s`, i.e.,
-``n`` if the set is a subset of ``\\mathbb{R}^n``.
-"""
 dimension(s::AbstractVectorSet) = s.dimension # .dimension field is conventional, overwrite this method if not applicable
 
 """
@@ -184,7 +188,7 @@ dimension(s::Union{ExponentialCone, DualExponentialCone, PowerCone, DualPowerCon
 
 The (vectorized) cone of symmetric positive semidefinite matrices, with side length `dimension` and with off-diagonals unscaled.
 The entries of the upper triangular part of the matrix are given column by column (or equivalently, the entries of the lower triangular part are given row by row).
-An ``dimension \\times dimension`` matrix has ``dimension(dimension+1)/2`` lower-triangular elements, so for the vectorized cone of dimension ``n``, the corresponding symmetric matrix has side dimension ``\\sqrt{1/4 + 2 n} - 1/2`` elements.
+An ``dimension \\times dimension`` matrix has ``dimension * (dimension+1)/2`` lower-triangular elements, so for the vectorized cone of dimension ``n``, the corresponding symmetric matrix has side dimension ``\\sqrt{1/4 + 2 n} - 1/2`` elements.
 
 ### Examples
 

test/sets.jl

@@ -3,3 +3,16 @@
     @test MOIU.getconstant(MOI.GreaterThan(6)) == 6
     @test MOIU.getconstant(MOI.LessThan(2)) == 2
 end
+
+@testset "Set dimension" begin
+    @test MOI.dimension(MOI.EqualTo(3.0)) === 1
+    @test MOI.dimension(MOI.Reals(8)) === 8
+    @test MOI.dimension(MOI.DualExponentialCone()) === 3
+    @test MOI.dimension(MOI.PositiveSemidefiniteConeTriangle(4)) === 10
+    @test MOI.dimension(MOI.PositiveSemidefiniteConeSquare(5)) === 25
+    @test MOI.dimension(MOI.RootDetConeTriangle(6)) === 22
+    @test MOI.dimension(MOI.LogDetConeTriangle(6)) === 22
+    @test MOI.dimension(MOI.RootDetConeSquare(4)) === 17
+    @test MOI.dimension(MOI.LogDetConeSquare(4)) === 17
+    @test MOI.dimension(MOI.SOS2(collect(1 : 6))) === 6
+end