add kwarg to disable checking number of equations and states agree (#1021)

* add ability to disable check_eqs_u0

* tweak error message

* remove @show

* disable length checks for ReactionSystems

Author: isaacsas

src/systems/abstractsystem.jl

@@ -665,15 +665,17 @@ AbstractTrees.children(sys::ModelingToolkit.AbstractSystem) = ModelingToolkit.ge
 AbstractTrees.printnode(io::IO, sys::ModelingToolkit.AbstractSystem) = print(io, nameof(sys))
 AbstractTrees.nodetype(::ModelingToolkit.AbstractSystem) = ModelingToolkit.AbstractSystem
 
-function check_eqs_u0(eqs, dvs, u0)
+function check_eqs_u0(eqs, dvs, u0; check_length=true, kwargs...)
     if u0 !== nothing
-        if !(length(eqs) == length(dvs) == length(u0))
-            throw(ArgumentError("Equations ($(length(eqs))), states ($(length(dvs))), and initial conditions ($(length(u0))) are of different lengths."))
-        end
-    else
-        if !(length(eqs) == length(dvs))
-            throw(ArgumentError("Equations ($(length(eqs))), states ($(length(dvs))) are of different lengths."))
+        if check_length
+            if !(length(eqs) == length(dvs) == length(u0))
+                throw(ArgumentError("Equations ($(length(eqs))), states ($(length(dvs))), and initial conditions ($(length(u0))) are of different lengths. To allow a different number of equations than states use kwarg check_length=false."))
+            end
+        elseif length(dvs) != length(u0)
+            throw(ArgumentError("States ($(length(dvs))) and initial conditions ($(length(u0))) are of different lengths."))
         end
+    elseif check_length && (length(eqs) != length(dvs))
+        throw(ArgumentError("Equations ($(length(eqs))) and states ($(length(dvs))) are of different lengths. To allow these to differ use kwarg check_length=false."))
     end
     return nothing
 end

src/systems/diffeqs/abstractodesystem.jl

@@ -426,7 +426,7 @@ function process_DEProblem(constructor, sys::AbstractODESystem,u0map,parammap;
     end
     p = varmap_to_vars(parammap,ps; defaults=pdefs)
 
-    check_eqs_u0(eqs, dvs, u0)
+    check_eqs_u0(eqs, dvs, u0; kwargs...)
 
     f = constructor(sys,dvs,ps,u0;ddvs=ddvs,tgrad=tgrad,jac=jac,checkbounds=checkbounds,
                     linenumbers=linenumbers,parallel=parallel,simplify=simplify,

src/systems/nonlinear/nonlinearsystem.jl

@@ -226,7 +226,7 @@ function process_NonlinearProblem(constructor, sys::NonlinearSystem,u0map,paramm
     u0 = varmap_to_vars(u0map,dvs; defaults=defs)
     p = varmap_to_vars(parammap,ps; defaults=defs)
 
-    check_eqs_u0(eqs, dvs, u0)
+    check_eqs_u0(eqs, dvs, u0; kwargs...)
 
     f = constructor(sys,dvs,ps,u0;jac=jac,checkbounds=checkbounds,
                     linenumbers=linenumbers,parallel=parallel,simplify=simplify,

src/systems/reaction/reactionsystem.jl

@@ -506,13 +506,13 @@ end
 
 
 # ODEProblem from AbstractReactionNetwork
-function DiffEqBase.ODEProblem(rs::ReactionSystem, u0, tspan, p=DiffEqBase.NullParameters(), args...; kwargs...)
-    return ODEProblem(convert(ODESystem,rs; kwargs...),u0,tspan,p, args...; kwargs...)
+function DiffEqBase.ODEProblem(rs::ReactionSystem, u0, tspan, p=DiffEqBase.NullParameters(), args...; check_length=false, kwargs...)
+    return ODEProblem(convert(ODESystem,rs; kwargs...),u0,tspan,p, args...; check_length, kwargs...)
 end
 
 # NonlinearProblem from AbstractReactionNetwork
-function DiffEqBase.NonlinearProblem(rs::ReactionSystem, u0, p=DiffEqBase.NullParameters(), args...; kwargs...)
-    return NonlinearProblem(convert(NonlinearSystem,rs; kwargs...), u0, p, args...; kwargs...)
+function DiffEqBase.NonlinearProblem(rs::ReactionSystem, u0, p=DiffEqBase.NullParameters(), args...; check_length=false, kwargs...)
+    return NonlinearProblem(convert(NonlinearSystem,rs; kwargs...), u0, p, args...; check_length, kwargs...)
 end
 
 

test/odesystem.jl

@@ -330,3 +330,13 @@ sys = ode_order_lowering(sys)
 prob = ODEProblem(sys, [], tspan)
 sol = solve(prob, Tsit5())
 @test sum(abs, sol[end]) < 1
+
+
+# check_eqs_u0 kwarg test
+@parameters t
+@variables x1(t) x2(t)
+D =Differential(t)
+eqs = [D(x1) ~ -x1]
+sys = ODESystem(eqs,t,[x1,x2],[])
+@test_throws ArgumentError ODEProblem(sys, [1.0,1.0], (0.0,1.0))
+prob = ODEProblem(sys, [1.0,1.0], (0.0,1.0), check_length=false)