fix: remake initialization problem during DAE initialization

Author: AayushSabharwal

Project.toml

@@ -42,6 +42,7 @@ SparseArrays = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
 SparseDiffTools = "47a9eef4-7e08-11e9-0b38-333d64bd3804"
 StaticArrayInterface = "0d7ed370-da01-4f52-bd93-41d350b8b718"
 StaticArrays = "90137ffa-7385-5640-81b9-e52037218182"
+SymbolicIndexingInterface = "2efcf032-c050-4f8e-a9bb-153293bab1f5"
 TruncatedStacktraces = "781d530d-4396-4725-bb49-402e4bee1e77"
 
 [compat]
@@ -84,6 +85,7 @@ SparseArrays = "1.9"
 SparseDiffTools = "2.3"
 StaticArrayInterface = "1.2"
 StaticArrays = "1.0"
+SymbolicIndexingInterface = "0.3.16"
 TruncatedStacktraces = "1.2"
 julia = "1.10"
 

src/OrdinaryDiffEq.jl

@@ -64,6 +64,8 @@ using ExponentialUtilities
 
 using NonlinearSolve
 
+using SymbolicIndexingInterface
+
 # Required by temporary fix in not in-place methods with 12+ broadcasts
 # `MVector` is used by Nordsieck forms
 import StaticArrays: SArray, MVector, SVector, @SVector, StaticArray, MMatrix, SA

src/initialize_dae.jl

@@ -134,7 +134,16 @@ end
 function _initialize_dae!(integrator, prob::Union{ODEProblem, DAEProblem},
         alg::OverrideInit, isinplace::Union{Val{true}, Val{false}})
     initializeprob = prob.f.initializeprob
-
+    if initializeprob.f.sys !== nothing && prob.f.sys !== nothing
+        initu0vars = variable_symbols(initializeprob)
+        initu0order = variable_index.((initializeprob,), initu0vars)
+        # Variable symbols are not guaranteed to be in order
+        invpermute!(initu0vars, initu0order)
+        initu0 = getu(prob.f.initializeprob, initu0vars)(prob)
+        initp = remake_buffer(initializeprob, parameter_values(initializeprob),
+            Dict(sym => getu(prob, sym)(prob) for sym in parameter_symbols(initializeprob)))
+        initializeprob = remake(initializeprob; u0 = initu0, p = initp)
+    end
     # If it doesn't have autodiff, assume it comes from symbolic system like ModelingToolkit
     # Since then it's the case of not a DAE but has initializeprob
     # In which case, it should be differentiable