Merge pull request #2809 from dcourteville/fix_backward_callback

Add tests for event detection when step is exactly on event date

Author: ChrisRackauckas

lib/OrdinaryDiffEqCore/Project.toml

@@ -51,7 +51,7 @@ Accessors = "0.1.36"
 Adapt = "3.0, 4"
 ArrayInterface = "7"
 DataStructures = "0.18"
-DiffEqBase = "6.169.1"
+DiffEqBase = "6.182.0"
 DiffEqDevTools = "2.44.4"
 DocStringExtensions = "0.9"
 EnumX = "1"

test/integrators/ode_event_tests.jl

@@ -22,6 +22,10 @@ callback = ContinuousCallback(condition, affect!)
 sol = solve(prob, Tsit5(), callback = callback)
 @test length(sol) < 20
 
+# Force integrator to step on event
+sol = solve(prob, Tsit5(), callback = callback, tstops = [-2.95])
+@test sol(-2.95, continuity = :right) ≈ sol(-2.95, continuity = :left) + 2
+
 condition = function (out, u, t, integrator) # Event when event_f(u,t,k) == 0
     out[1] = -t - 2.95
 end
@@ -36,6 +40,10 @@ callback = VectorContinuousCallback(condition, affect!, 1)
 
 sol = solve(prob, Tsit5(), callback = callback)
 
+# Force integrator to step on event
+sol = solve(prob, Tsit5(), callback = callback, tstops = [-2.95])
+@test sol(-2.95, continuity = :right) ≈ sol(-2.95, continuity = :left) + 2
+
 f = function (du, u, p, t)
     du[1] = -u[1] + sin(t)
 end
@@ -54,6 +62,10 @@ callback = ContinuousCallback(condition, affect!)
 
 sol = solve(prob, Tsit5(), callback = callback, abstol = 1e-8, reltol = 1e-6)
 
+# Force integrator to step on event
+sol = solve(prob, Tsit5(), callback = callback, abstol = 1e-8, reltol = 1e-6, tstops = [2.95])
+@test sol(2.95, continuity = :right)[1] ≈ sol(2.95, continuity = :left)[1] + 2
+
 condition = function (out, u, t, integrator) # Event when event_f(u,t,k) == 0
     out[1] = t - 2.95
 end
@@ -68,6 +80,10 @@ callback = VectorContinuousCallback(condition, affect!, 1)
 
 sol = solve(prob, Tsit5(), callback = callback, abstol = 1e-8, reltol = 1e-6)
 
+# Force integrator to step on event
+sol = solve(prob, Tsit5(), callback = callback, abstol = 1e-8, reltol = 1e-6, tstops = [2.95])
+@test sol(2.95, continuity = :right)[1] ≈ sol(2.95, continuity = :left)[1] + 2
+
 f = function (du, u, p, t)
     du[1] = u[2]
     du[2] = -9.81