Add constructor without type

NEWS.md

@@ -1,3 +1,14 @@
+## VortexStepMethod v3.3.0 2026-05-05
+
+### Added
+- `ForwardDiff` compatibility, used by default in `linearize` (#232)
+- `backend` keyword argument for `linearize`
+- example `linearize_check.jl` comparing FiniteDiff and ForwardDiff tangents
+
+### Changed
+- core structs are parameterized on the scalar type `T` so dual numbers can
+  propagate through them; public constructors are unchanged
+
 ## VortexStepMethod v3.2.0 2026-05-02
 
 ### Added

Project.toml

@@ -1,7 +1,7 @@
 name = "VortexStepMethod"
 uuid = "ed3cd733-9f0f-46a9-93e0-89b8d4998dd9"
 authors = ["1-Bart-1 <bart@vandelint.net>", "Oriol Cayon and contributors"]
-version = "3.2.0"
+version = "3.3.0"
 
 [workspace]
 projects = ["examples", "examples_cp", "docs", "test"]

docs/src/types.md

@@ -36,7 +36,7 @@ A body is constructed of one or more abstract wings. All wings are of type Wing.
 A Wing has one or more sections and can be created from YAML files or OBJ geometry.
 ```@docs
 Section
-Section(LE_point::PosVector, TE_point::PosVector, aero_model)
+Section(LE_point, TE_point, aero_model)
 Wing
 Wing(n_panels::Int; spanwise_distribution::PanelDistribution=LINEAR,
      spanwise_direction::PosVector=MVec3([0.0, 1.0, 0.0]))

src/wing_geometry.jl

@@ -1,23 +1,29 @@
 """
-    @with_kw mutable struct Section
+    mutable struct Section{T}
 
 Represents a wing section with leading edge, trailing edge, and aerodynamic properties.
 
 # Fields
-- `LE_point::MVec3` = zeros(MVec3): Leading edge point coordinates
-- `TE_point::MVec3` = zeros(MVec3): Trailing edge point coordinates
-- `aero_model`::AeroModel = INVISCID: [AeroModel](@ref)
-- `aero_data`::AeroData = nothing: See: [AeroData](@ref)
+- `LE_point::MVector{3, T}`: Leading edge point coordinates
+- `TE_point::MVector{3, T}`: Trailing edge point coordinates
+- `aero_model::AeroModel`: [AeroModel](@ref)
+- `aero_data::AeroData`: See: [AeroData](@ref)
 """
-@with_kw mutable struct Section{T}
-    LE_point::MVector{3, T} = zeros(MVector{3, T})
-    TE_point::MVector{3, T} = zeros(MVector{3, T})
-    aero_model::AeroModel = INVISCID
-    aero_data::AeroData = nothing
+mutable struct Section{T}
+    LE_point::MVector{3, T}
+    TE_point::MVector{3, T}
+    aero_model::AeroModel
+    aero_data::AeroData
 end
 
+Section{T}(; LE_point=zeros(MVector{3, T}), TE_point=zeros(MVector{3, T}),
+           aero_model=INVISCID, aero_data=nothing) where {T} =
+    Section{T}(LE_point, TE_point, aero_model, aero_data)
+
+Section() = Section{Float64}()
+
 """
-    Section(LE_point::PosVector, TE_point::PosVector, aero_model)
+    Section(LE_point, TE_point, aero_model)
 
 Create a new wing section with the specified leading edge point, trailing edge point,
 and aerodynamic model.

test/wing_geometry/test_wing_geometry.jl

@@ -20,6 +20,15 @@ function ==(a::Section, b::Section)
 end
 
 @testset "Wing Geometry Tests" begin
+    @testset "Section default constructor" begin
+        s = Section()
+        @test s isa Section{Float64}
+        @test s.LE_point == zeros(3)
+        @test s.TE_point == zeros(3)
+        @test s.aero_model === INVISCID
+        @test isnothing(s.aero_data)
+    end
+
     @testset "Wing initialization" begin
         example_wing = Wing(10; spanwise_distribution=LINEAR)
         @test example_wing.n_panels == 10