From ccc8003858297324d6d0f1a4e024500f61f666d2 Mon Sep 17 00:00:00 2001
From: "Klamkin, Michael" <mklamkin3@gatech.edu>
Date: Sat, 7 Jun 2025 20:18:58 -0400
Subject: [PATCH 1/2] add getter for dual slack variable from quadratic
 objective

---
 ext/DualizationJuMPExt/DualizationJuMPExt.jl | 10 ++++++++++
 src/structures.jl                            |  4 ++++
 2 files changed, 14 insertions(+)

diff --git a/ext/DualizationJuMPExt/DualizationJuMPExt.jl b/ext/DualizationJuMPExt/DualizationJuMPExt.jl
index b59ec67..a42ce06 100644
--- a/ext/DualizationJuMPExt/DualizationJuMPExt.jl
+++ b/ext/DualizationJuMPExt/DualizationJuMPExt.jl
@@ -146,4 +146,14 @@ function Dualization._get_dual_parameter(
     return JuMP.VariableRef(dual_model, moi_dual_vi)
 end
 
+function Dualization._get_dual_slack_variable(
+    dual_model::JuMP.Model,
+    primal_ref::JuMP.VariableRef,
+)
+    map = _get_primal_dual_map(dual_model)
+    moi_primal_vi = JuMP.index(primal_ref)
+    moi_dual_vi = Dualization._get_dual_slack_variable(map, moi_primal_vi)
+    return JuMP.VariableRef(dual_model, moi_dual_vi)
+end
+
 end # module DualizationJuMPExt
diff --git a/src/structures.jl b/src/structures.jl
index 6fc5914..3063a81 100644
--- a/src/structures.jl
+++ b/src/structures.jl
@@ -184,6 +184,10 @@ function _get_dual_parameter(m::PrimalDualMap, vi::MOI.VariableIndex)
     return m.primal_parameter_to_dual_parameter[vi]
 end
 
+function _get_dual_slack_variable(m::PrimalDualMap, vi::MOI.VariableIndex)
+    return m.primal_var_in_quad_obj_to_dual_slack_var[vi]
+end
+
 function Base.getproperty(m::PrimalDualMap{T}, name::Symbol) where {T}
     if name === :constrained_var_idx
         error(

From f0ee9161cbffeaa2a67adbc9afdf324afad7fc59 Mon Sep 17 00:00:00 2001
From: "Klamkin, Michael" <mklamkin3@gatech.edu>
Date: Sun, 8 Jun 2025 15:41:50 -0400
Subject: [PATCH 2/2] add test

---
 test/Tests/test_JuMP_dualize.jl | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/test/Tests/test_JuMP_dualize.jl b/test/Tests/test_JuMP_dualize.jl
index 47c1c9a..4058ef0 100644
--- a/test/Tests/test_JuMP_dualize.jl
+++ b/test/Tests/test_JuMP_dualize.jl
@@ -128,4 +128,20 @@ end
         con = Dualization._get_dual_constraint(dual_model, cv)
         @test con isa ConstraintRef
     end
+    @testset "JuMP parametric quadratic" begin
+        model = Model()
+        @variable(model, x)
+        @variable(model, p ∈ Parameter(2.0))
+        @constraint(model, c, x <= p)
+        @objective(model, Max, 3x + x^2)
+        dual_model = dualize(model, dual_names=DualNames())
+        param = Dualization._get_dual_parameter(dual_model, p)
+        @test param isa VariableRef
+        @test owner_model(param) === dual_model
+        @test MOI.get(dual_model, MOI.VariableName(), param) == "param_p"
+        quadslack = Dualization._get_dual_slack_variable(dual_model, x)
+        @test quadslack isa VariableRef
+        @test owner_model(quadslack) === dual_model
+        @test MOI.get(dual_model, MOI.VariableName(), quadslack) == "quadslack_x"
+    end
 end