Merge pull request #2155 from SciML/uprev

Reset uprev with reinitializations

Author: ChrisRackauckas

src/integrators/integrator_interface.jl

@@ -38,6 +38,7 @@ function DiffEqBase.reeval_internals_due_to_modification!(
         integrator::ODEIntegrator, continuous_modification = true)
     if integrator.isdae
         DiffEqBase.initialize_dae!(integrator)
+        update_uprev!(integrator)
     end
 
     if continuous_modification && integrator.opts.calck

src/solve.jl

@@ -495,6 +495,7 @@ function DiffEqBase.__init(
     if initialize_integrator
         if isdae || SciMLBase.has_initializeprob(prob.f)
             DiffEqBase.initialize_dae!(integrator)
+            update_uprev!(integrator)
         end
 
         if save_start

test/interface/dae_initialize_integration.jl

@@ -59,3 +59,16 @@ prob = ODEProblem(_f, [0.0], (0.0, 1.0))
 sol = solve(prob, Tsit5())
 @test SciMLBase.successful_retcode(sol)
 @test sol[1] == [1.0]
+
+prob = ODEProblem(_f, [0.0], (0.0,1.0))
+sol = solve(prob, Tsit5(), dt = 1e-10)
+@test SciMLBase.successful_retcode(sol)
+@test sol[1] == [1.0]
+@test sol[2] ≈ [0.9999999998]
+@test sol[end] ≈ [-1.0]
+
+sol = solve(prob, Rodas5P(), dt = 1e-10)
+@test SciMLBase.successful_retcode(sol)
+@test sol[1] == [1.0]
+@test sol[2] ≈ [0.9999999998]
+@test sol[end] ≈ [-1.0]