Dual Variables Dimension Clarification

src/CTModels.jl

@@ -266,4 +266,4 @@ include(joinpath(@__DIR__, "nlp", "discretized_ocp.jl"))
 include(joinpath(@__DIR__, "nlp", "model_api.jl"))
 include(joinpath(@__DIR__, "init", "initial_guess.jl"))
 
-end
+end

src/ocp/model.jl

@@ -16,8 +16,18 @@ Appends box constraint data to the provided vectors.
 # Notes
 - All input vectors (`rg`, `lb`, `ub`) must have the same length.
 - The function modifies the `inds`, `lbs`, `ubs`, and `labels` vectors in-place.
+- If a component index already exists in `inds`, a warning is emitted indicating that the
+  previous bound will be overwritten by the new constraint. The dual variable dimension
+  remains equal to the state/control/variable dimension, not the number of constraint declarations.
 """
 function append_box_constraints!(inds, lbs, ubs, labels, rg, lb, ub, label)
+    # Check for duplicate indices and emit warning
+    for idx in rg
+        if idx in inds
+            @warn "Overwriting bound for component $idx (label: $label). Previous value will be discarded. " *
+                  "Note: dual variable dimension equals the state/control/variable dimension, not the number of constraints."
+        end
+    end
     append!(inds, rg)
     append!(lbs, lb)
     append!(ubs, ub)
@@ -26,6 +36,7 @@ function append_box_constraints!(inds, lbs, ubs, labels, rg, lb, ub, label)
     end
 end
 
+
 """
 $(TYPEDSIGNATURES)
 

src/ocp/solution.jl

@@ -31,7 +31,15 @@ Build a solution from the optimal control problem, the time grid, the state, con
 
 - `sol::Solution`: the optimal control solution.
 
+# Notes
+
+The dimensions of box constraint dual variables (`state_constraints_*_dual`, `control_constraints_*_dual`, 
+`variable_constraints_*_dual`) correspond to the **state/control/variable dimension**, not the number of 
+constraint declarations. If multiple constraints are declared on the same component (e.g., `x₂(t) ≤ 1.2` 
+and `x₂(t) ≤ 2.0`), only the last bound value is retained, and a warning is emitted during model construction.
+
 """
+
 function build_solution(
     ocp::Model,
     T::Vector{Float64},

test/ocp/test_constraints.jl

@@ -136,4 +136,70 @@ function test_constraints()
     # test with :variable constraint and range
     CTModels.constraint!(ocp_set, :variable; rg=1:1, lb=[1], ub=[1], label=:variable_rg)
     @test ocp_set.constraints[:variable_rg] == (:variable, 1:1, [1], [1])
+
+    # -----------------------------------------------------------------------
+    # Test duplicate constraint warning (Issue #105)
+    # When multiple constraints are declared on the same component index,
+    # a warning should be emitted during model build.
+    # Applies to: state, control, and variable constraints.
+    # -----------------------------------------------------------------------
+    @testset "duplicate constraint warning" begin
+        # --- State constraints ---
+        @testset "state" begin
+            ocp_dup = CTModels.PreModel()
+            CTModels.time!(ocp_dup; t0=0.0, tf=1.0)
+            CTModels.state!(ocp_dup, 2)
+            CTModels.control!(ocp_dup, 1)
+            dynamics!(r, t, x, u, v) = r .= [x[1], u[1]]
+            CTModels.dynamics!(ocp_dup, dynamics!)
+            CTModels.objective!(ocp_dup, :min; mayer=(x0, xf, v) -> xf[1])
+            CTModels.definition!(ocp_dup, quote end)
+            CTModels.time_dependence!(ocp_dup; autonomous=false)
+
+            # Add constraints on state component 1
+            CTModels.constraint!(ocp_dup, :state; rg=1:1, lb=[0.0], ub=[1.0], label=:s1)
+            CTModels.constraint!(ocp_dup, :state; rg=1:1, lb=[0.5], ub=[1.5], label=:s2)
+
+            @test_warn "Overwriting bound for component 1" CTModels.build(ocp_dup)
+        end
+
+        # --- Control constraints ---
+        @testset "control" begin
+            ocp_dup = CTModels.PreModel()
+            CTModels.time!(ocp_dup; t0=0.0, tf=1.0)
+            CTModels.state!(ocp_dup, 2)
+            CTModels.control!(ocp_dup, 2)  # 2 controls to allow duplicate on component 1
+            dynamics!(r, t, x, u, v) = r .= [x[1], u[1]]
+            CTModels.dynamics!(ocp_dup, dynamics!)
+            CTModels.objective!(ocp_dup, :min; mayer=(x0, xf, v) -> xf[1])
+            CTModels.definition!(ocp_dup, quote end)
+            CTModels.time_dependence!(ocp_dup; autonomous=false)
+
+            # Add constraints on control component 1
+            CTModels.constraint!(ocp_dup, :control; rg=1:1, lb=[0.0], ub=[1.0], label=:c1)
+            CTModels.constraint!(ocp_dup, :control; rg=1:1, lb=[0.5], ub=[1.5], label=:c2)
+
+            @test_warn "Overwriting bound for component 1" CTModels.build(ocp_dup)
+        end
+
+        # --- Variable constraints ---
+        @testset "variable" begin
+            ocp_dup = CTModels.PreModel()
+            CTModels.time!(ocp_dup; t0=0.0, tf=1.0)
+            CTModels.state!(ocp_dup, 2)
+            CTModels.control!(ocp_dup, 1)
+            CTModels.variable!(ocp_dup, 2)  # 2 variables to allow duplicate on component 1
+            dynamics!(r, t, x, u, v) = r .= [x[1], u[1]]
+            CTModels.dynamics!(ocp_dup, dynamics!)
+            CTModels.objective!(ocp_dup, :min; mayer=(x0, xf, v) -> xf[1])
+            CTModels.definition!(ocp_dup, quote end)
+            CTModels.time_dependence!(ocp_dup; autonomous=false)
+
+            # Add constraints on variable component 1
+            CTModels.constraint!(ocp_dup, :variable; rg=1:1, lb=[0.0], ub=[1.0], label=:v1)
+            CTModels.constraint!(ocp_dup, :variable; rg=1:1, lb=[0.5], ub=[1.5], label=:v2)
+
+            @test_warn "Overwriting bound for component 1" CTModels.build(ocp_dup)
+        end
+    end
 end