Add methods for Base.complex (#3734)

src/operators.jl

@@ -531,3 +531,40 @@ function Base.:*(
 )
     return x * A
 end
+
+function Base.complex(
+    r::Union{
+        GenericVariableRef{<:Real},
+        GenericAffExpr{<:Real},
+        GenericQuadExpr{<:Real},
+    },
+    i::Real,
+)
+    return r + im * i
+end
+
+function Base.complex(
+    r::Real,
+    i::Union{
+        GenericVariableRef{<:Real},
+        GenericAffExpr{<:Real},
+        GenericQuadExpr{<:Real},
+    },
+)
+    return r + im * i
+end
+
+function Base.complex(
+    r::Union{
+        GenericVariableRef{<:Real},
+        GenericAffExpr{<:Real},
+        GenericQuadExpr{<:Real},
+    },
+    i::Union{
+        GenericVariableRef{<:Real},
+        GenericAffExpr{<:Real},
+        GenericQuadExpr{<:Real},
+    },
+)
+    return r + im * i
+end

src/quad_expr.jl

@@ -108,6 +108,17 @@ function GenericQuadExpr{V,K}(aff::GenericAffExpr{V,K}, kv::Pair...) where {K,V}
     )
 end
 
+function GenericQuadExpr(
+    aff::GenericAffExpr{T,V},
+    quad::OrderedDict{UnorderedPair{V},S},
+) where {T,S,V}
+    C = promote_type(T, S)
+    return GenericQuadExpr(
+        convert(GenericAffExpr{C,V}, aff),
+        convert(OrderedDict{UnorderedPair{V},C}, quad),
+    )
+end
+
 function Base.iszero(expr::GenericQuadExpr)
     return iszero(expr.aff) && all(iszero, values(expr.terms))
 end

test/test_operator.jl

@@ -673,4 +673,20 @@ function test_matrix_abstractscalar_add()
     return
 end
 
+function test_base_complex()
+    model = Model()
+    @variable(model, x)
+    for f in (x, 1.0 * x, x^2)
+        @test isequal_canonical(complex(3, f), 3 + im * f)
+        @test isequal_canonical(complex(f, 2.0), f + 2.0im)
+    end
+    for f in (x, 1.0 * x, x^2), g in (x, 1.0 * x, x^2)
+        @test isequal_canonical(complex(f, g), f + im * g)
+    end
+    @test_throws MethodError complex(x, 2im)
+    @test_throws MethodError complex(2im, x)
+    @test_throws MethodError complex(2.0 + x, im * x)
+    return
+end
+
 end