WIP

Author: YingboMa

src/systems/clock_inference.jl

@@ -130,7 +130,6 @@ function split_system(ci::ClockInference)
         fadj = Vector{Int}[]
         eqs_i = Equation[]
         eq_to_diff = DiffGraph(length(ieqs))
-        var_set_i = BitSet(vars)
         ne = 0
         for (j, eq_i) in enumerate(ieqs)
             vars = copy(graph.fadjlist[eq_i])

src/systems/systemstructure.jl

@@ -258,6 +258,30 @@ function TearingState(sys; quick_cancel = false, check = true)
                 idx = addvar!(dvar)
             end
 
+            dvar = var
+            idx = varidx
+            if ModelingToolkit.isoperator(dvar, ModelingToolkit.Shift)
+                if !(idx in dervaridxs)
+                    push!(dervaridxs, idx)
+                end
+                op = operation(dvar)
+                tt = op.t
+                steps = op.steps
+                v = arguments(dvar)[1]
+                for s in (steps - 1):-1:1
+                    sf = Shift(tt, s)
+                    dvar = sf(v)
+                    idx = addvar!(dvar)
+                    if !(idx in dervaridxs)
+                        push!(dervaridxs, idx)
+                    end
+                end
+                idx = addvar!(v)
+                #if !(idx in dervaridxs)
+                #    push!(dervaridxs, idx)
+                #end
+            end
+
             if istree(var) && operation(var) isa Symbolics.Operator &&
                !isdifferential(var) && (it = input_timedomain(var)) !== nothing
                 set_incidence = false

test/clock.jl

@@ -11,6 +11,7 @@ dt = 0.1
 @variables t x(t) y(t) u(t) yd(t) ud(t) r(t)
 @parameters kp
 D = Differential(t)
+# u(n + 1) := f(u(n))
 
 eqs = [yd ~ Sample(t, dt)(y)
        ud ~ kp * (r - yd)
@@ -85,6 +86,34 @@ d = Clock(t, dt)
 @test varmap[y] == Continuous()
 @test varmap[u] == Continuous()
 
+@info "Testing shift normalization"
+dt = 0.1
+@variables t x(t) y(t) u(t) yd(t) ud(t) r(t) z(t)
+@parameters kp
+D = Differential(t)
+d = Clock(t, dt)
+k = ShiftIndex(d)
+
+eqs = [yd ~ Sample(t, dt)(y)
+       ud ~ kp * (r - yd)
+       r ~ 1.0
+
+       # plant (time continuous part)
+       u ~ Hold(ud)
+       D(x) ~ -x + u
+       y ~ x
+       z(k + 2) ~ z(k) + yd
+       #=
+       z(k + 2) ~ z(k)
+       =>
+       z′(k + 1) ~ z(k)
+       z(k + 1)  ~ z′(k)
+       =#
+       ]
+@named sys = ODESystem(eqs)
+ci, varmap = infer_clocks(sys)
+tss, inputs = ModelingToolkit.split_system(deepcopy(ci))
+
 @info "Testing multi-rate hybrid system"
 dt = 0.1
 dt2 = 0.2