Use DiffEqBase extended initialization algorithms

Now that DiffEqBase has the extended versions of BrownBasicInit and ShampineCollocationInit with parameters, OrdinaryDiffEq can use them directly instead of maintaining its own extended types.

Changes:
- Import BrownFullBasicInit from DiffEqBase
- Remove local extended type definitions
- Create aliases for backward compatibility
- Update OrdinaryDiffEqNonlinearSolve to use DiffEqBase types

This simplifies the code and reduces duplication across the ecosystem.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: ChrisRackauckas

lib/OrdinaryDiffEqCore/src/initialize_dae.jl

@@ -1,42 +1,13 @@
-# Import standard initialization algorithms from DiffEqBase
-import DiffEqBase: DefaultInit, ShampineCollocationInit, BrownBasicInit
+# Import all initialization algorithms from DiffEqBase
+import DiffEqBase: DefaultInit, ShampineCollocationInit, BrownBasicInit, BrownFullBasicInit
 
 # Re-export for backward compatibility
-export DefaultInit, ShampineCollocationInit, BrownBasicInit
+export DefaultInit, ShampineCollocationInit, BrownBasicInit, BrownFullBasicInit
 
-# Extended versions with OrdinaryDiffEq-specific options
-struct ShampineCollocationInitExt{T, F} <: SciMLBase.DAEInitializationAlgorithm
-    initdt::T
-    nlsolve::F
-end
-function ShampineCollocationInitExt(; initdt = nothing, nlsolve = nothing)
-    ShampineCollocationInitExt(initdt, nlsolve)
-end
-function ShampineCollocationInitExt(initdt)
-    ShampineCollocationInitExt(; initdt = initdt, nlsolve = nothing)
-end
-
-# Constructor for backward compatibility when passing initdt
-function ShampineCollocationInit(initdt::T) where T
-    ShampineCollocationInitExt(; initdt = initdt, nlsolve = nothing)
-end
-
-struct BrownFullBasicInit{T, F} <: SciMLBase.DAEInitializationAlgorithm
-    abstol::T
-    nlsolve::F
-end
-function BrownFullBasicInit(; abstol = 1e-10, nlsolve = nothing)
-    BrownFullBasicInit(abstol, nlsolve)
-end
-BrownFullBasicInit(abstol) = BrownFullBasicInit(; abstol = abstol, nlsolve = nothing)
-
-# Alias for consistency with DiffEqBase naming
+# Legacy aliases for backward compatibility
+const ShampineCollocationInitExt = ShampineCollocationInit
 const BrownBasicInitExt = BrownFullBasicInit
-
-# Constructor for backward compatibility when passing abstol
-function BrownBasicInit(abstol::T) where T
-    BrownFullBasicInit(abstol, nothing)
-end
+export ShampineCollocationInitExt, BrownBasicInitExt
 
 ## Notes
 

lib/OrdinaryDiffEqNonlinearSolve/src/initialize_dae.jl

@@ -17,32 +17,20 @@ end
 end
 
 # Helper to get abstol from either the algorithm or integrator opts
-@inline function get_abstol(alg::Union{BrownFullBasicInit, OrdinaryDiffEqCore.BrownFullBasicInit}, integrator)
+@inline function get_abstol(alg::Union{DiffEqBase.BrownBasicInit, DiffEqBase.BrownFullBasicInit}, integrator)
     return alg.abstol
 end
 
-@inline function get_abstol(alg::DiffEqBase.BrownBasicInit, integrator)
-    return integrator.opts.abstol
-end
-
 # Helper to get nlsolve from either the algorithm or nothing
-@inline function get_nlsolve(alg::Union{BrownFullBasicInit, OrdinaryDiffEqCore.BrownFullBasicInit, OrdinaryDiffEqCore.ShampineCollocationInitExt})
+@inline function get_nlsolve(alg::Union{DiffEqBase.BrownBasicInit, DiffEqBase.BrownFullBasicInit, DiffEqBase.ShampineCollocationInit})
     return alg.nlsolve
 end
 
-@inline function get_nlsolve(alg::Union{DiffEqBase.BrownBasicInit, DiffEqBase.ShampineCollocationInit})
-    return nothing
-end
-
 # Helper to get initdt from either the algorithm or nothing
-@inline function get_initdt(alg::OrdinaryDiffEqCore.ShampineCollocationInitExt)
+@inline function get_initdt(alg::DiffEqBase.ShampineCollocationInit)
     return alg.initdt
 end
 
-@inline function get_initdt(alg::Union{DiffEqBase.ShampineCollocationInit, OrdinaryDiffEqCore.ShampineCollocationInit})
-    return nothing
-end
-
 function default_nlsolve(
         ::Nothing, isinplace::Val{true}, u, ::AbstractNonlinearProblem, autodiff = false)
     FastShortcutNonlinearPolyalg(;
@@ -80,7 +68,7 @@ Solve for `u`
 
 =#
 
-function _initialize_dae!(integrator, prob::ODEProblem, alg::Union{ShampineCollocationInit, OrdinaryDiffEqCore.ShampineCollocationInitExt},
+function _initialize_dae!(integrator, prob::ODEProblem, alg::DiffEqBase.ShampineCollocationInit,
         isinplace::Val{true})
     @unpack p, t, f = integrator
     M = integrator.f.mass_matrix
@@ -196,7 +184,7 @@ function _initialize_dae!(integrator, prob::ODEProblem, alg::Union{ShampineCollo
     return
 end
 
-function _initialize_dae!(integrator, prob::ODEProblem, alg::Union{ShampineCollocationInit, OrdinaryDiffEqCore.ShampineCollocationInitExt},
+function _initialize_dae!(integrator, prob::ODEProblem, alg::DiffEqBase.ShampineCollocationInit,
         isinplace::Val{false})
     @unpack p, t, f = integrator
     u0 = integrator.u
@@ -417,7 +405,7 @@ function algebraic_jacobian(jac_prototype::T, algebraic_eqs,
 end
 
 function _initialize_dae!(integrator, prob::ODEProblem,
-        alg::Union{BrownFullBasicInit, DiffEqBase.BrownBasicInit}, isinplace::Val{true})
+        alg::Union{DiffEqBase.BrownBasicInit, DiffEqBase.BrownFullBasicInit}, isinplace::Val{true})
     @unpack p, t, f = integrator
     u = integrator.u
     M = integrator.f.mass_matrix
@@ -498,7 +486,7 @@ function _initialize_dae!(integrator, prob::ODEProblem,
 end
 
 function _initialize_dae!(integrator, prob::ODEProblem,
-        alg::Union{BrownFullBasicInit, DiffEqBase.BrownBasicInit}, isinplace::Val{false})
+        alg::Union{DiffEqBase.BrownBasicInit, DiffEqBase.BrownFullBasicInit}, isinplace::Val{false})
     @unpack p, t, f = integrator
 
     u0 = integrator.u
@@ -566,7 +554,7 @@ function _initialize_dae!(integrator, prob::ODEProblem,
 end
 
 function _initialize_dae!(integrator, prob::DAEProblem,
-        alg::Union{BrownFullBasicInit, DiffEqBase.BrownBasicInit}, isinplace::Val{true})
+        alg::Union{DiffEqBase.BrownBasicInit, DiffEqBase.BrownFullBasicInit}, isinplace::Val{true})
     @unpack p, t, f = integrator
     differential_vars = prob.differential_vars
     u = integrator.u
@@ -648,7 +636,7 @@ function _initialize_dae!(integrator, prob::DAEProblem,
 end
 
 function _initialize_dae!(integrator, prob::DAEProblem,
-        alg::Union{BrownFullBasicInit, DiffEqBase.BrownBasicInit}, isinplace::Val{false})
+        alg::Union{DiffEqBase.BrownBasicInit, DiffEqBase.BrownFullBasicInit}, isinplace::Val{false})
     @unpack p, t, f = integrator
     differential_vars = prob.differential_vars