Add propagation of guesses from parameters and observed

Fixes #2716

Author: ChrisRackauckas

src/systems/diffeqs/abstractodesystem.jl

@@ -790,7 +790,8 @@ function get_u0_p(sys,
             @warn "Observed variables cannot be assigned initial values. Initial values for $u0s_in_obs will be ignored."
         end
     end
-    defs = mergedefaults(defs, u0map, dvs)
+    observedmap = todict(map(x->x.rhs => x.lhs,observed(sys)))
+    defs = mergedefaults(defs, observedmap, u0map, dvs)
     for (k, v) in defs
         if Symbolics.isarraysymbolic(k)
             ks = scalarize(k)
@@ -821,7 +822,9 @@ function get_u0(
     if parammap !== nothing
         defs = mergedefaults(defs, parammap, ps)
     end
-    defs = mergedefaults(defs, u0map, dvs)
+    obs = map(x->x.rhs => x.lhs, observed(sys))
+    observedmap = isempty(obs) ? Dict() : todict(obs)
+    defs = mergedefaults(defs, observedmap, u0map, dvs)
     if symbolic_u0
         u0 = varmap_to_vars(
             u0map, dvs; defaults = defs, tofloat = false, use_union = false, toterm)

src/systems/nonlinear/initializesystem.jl

@@ -31,7 +31,7 @@ function generate_initializesystem(sys::ODESystem;
     schedule = getfield(sys, :schedule)
 
     if schedule !== nothing
-        guessmap = [x[2] => get(guesses, x[1], default_dd_value)
+        guessmap = [x[1] => get(guesses, x[1], default_dd_value)
                     for x in schedule.dummy_sub]
         dd_guess = Dict(filter(x -> !isnothing(x[1]), guessmap))
         if u0map === nothing || isempty(u0map)

src/utils.jl

@@ -617,6 +617,18 @@ function mergedefaults(defaults, varmap, vars)
     end
 end
 
+function mergedefaults(defaults, observedmap, varmap, vars)
+    defs = if varmap isa Dict
+        merge(observedmap, defaults, varmap)
+    elseif eltype(varmap) <: Pair
+        merge(observedmap, defaults, Dict(varmap))
+    elseif eltype(varmap) <: Number
+        merge(observedmap, defaults, Dict(zip(vars, varmap)))
+    else
+        merge(observedmap, defaults)
+    end
+end
+
 @noinline function throw_missingvars_in_sys(vars)
     throw(ArgumentError("$vars are either missing from the variable map or missing from the system's unknowns/parameters list."))
 end

test/guess_propagation.jl

@@ -0,0 +1,75 @@
+using ModelingToolkit, OrdinaryDiffEq
+using ModelingToolkit: D, t_nounits as t
+using Test
+
+# Standard case
+
+@variables x(t) [guess = 2]
+@variables y(t)
+eqs = [D(x) ~ 1
+       x ~ y]
+initialization_eqs = [1 ~ exp(1 + x)]
+
+@named sys = ODESystem(eqs, t; initialization_eqs)
+sys = complete(structural_simplify(sys))
+tspan = (0.0, 0.2)
+prob = ODEProblem(sys, [], tspan, [])
+
+@test prob.f.initializeprob[y] == 2.0
+@test prob.f.initializeprob[x] == 2.0
+sol = solve(prob.f.initializeprob; show_trace=Val(true))
+
+# Guess via observed
+
+@variables x(t)
+@variables y(t) [guess = 2]
+eqs = [D(x) ~ 1
+       x ~ y]
+initialization_eqs = [1 ~ exp(1 + x)]
+
+@named sys = ODESystem(eqs, t; initialization_eqs)
+sys = complete(structural_simplify(sys))
+tspan = (0.0, 0.2)
+prob = ODEProblem(sys, [], tspan, [])
+
+@test prob.f.initializeprob[x] == 2.0
+@test prob.f.initializeprob[y] == 2.0
+sol = solve(prob.f.initializeprob; show_trace=Val(true))
+
+# Guess via parameter
+
+@parameters a = -1.0
+@variables x(t) [guess = a]
+
+eqs = [D(x) ~ a]
+
+initialization_eqs = [1 ~ exp(1 + x)]
+
+@named sys = ODESystem(eqs, t; initialization_eqs)
+sys = complete(structural_simplify(sys))
+
+tspan = (0.0, 0.2)
+prob = ODEProblem(sys, [], tspan, [])
+
+@test prob.f.initializeprob[x] == -1.0
+sol = solve(prob.f.initializeprob; show_trace=Val(true))
+
+# Guess via observed parameter
+
+@parameters a = -1.0
+@variables x(t)
+@variables y(t) [guess = a]
+
+eqs = [D(x) ~ a,
+       y ~ x]
+
+initialization_eqs = [1 ~ exp(1 + x)]
+
+@named sys = ODESystem(eqs, t; initialization_eqs)
+sys = complete(structural_simplify(sys))
+
+tspan = (0.0, 0.2)
+prob = ODEProblem(sys, [], tspan, [])
+
+@test prob.f.initializeprob[x] == -1.0
+sol = solve(prob.f.initializeprob; show_trace=Val(true))

test/runtests.jl

@@ -38,6 +38,7 @@ end
             @safetestset "DDESystem Test" include("dde.jl")
             @safetestset "NonlinearSystem Test" include("nonlinearsystem.jl")
             @safetestset "InitializationSystem Test" include("initializationsystem.jl")
+            @safetestset "Guess Propagation" include("guess_propagation.jl")
             @safetestset "Hierarchical Initialization Equations" include("hierarchical_initialization_eqs.jl")
             @safetestset "PDE Construction Test" include("pde.jl")
             @safetestset "JumpSystem Test" include("jumpsystem.jl")