Support ODESystem in the alternative build targets

Author: ChrisRackauckas

Project.toml

@@ -1,7 +1,7 @@
 name = "ModelingToolkit"
 uuid = "961ee093-0014-501f-94e3-6117800e7a78"
 authors = ["Chris Rackauckas <accounts@chrisrackauckas.com>"]
-version = "1.4.0"
+version = "1.4.1"
 
 [deps]
 DiffEqBase = "2b5f629d-d688-5b77-993f-72d75c75574e"

src/build_function.jl

@@ -116,7 +116,13 @@ function numbered_expr(O::Operation,vars,parameters;
          [numbered_expr(x,vars,parameters;derivname=derivname,
                         varname=varname,paramname=paramname) for x in O.args]...)
 end
-
+function numbered_expr(de::ModelingToolkit.DiffEq,vars,parameters;
+                       derivname=:du,varname=:u,paramname=:p)
+    i = findfirst(x->isequal(x.op.name,de.x.name),vars)
+    :($derivname[$i] = $(numbered_expr(de.rhs,vars,parameters;
+                                     derivname=derivname,
+                                     varname=varname,paramname=paramname)))
+end
 numbered_expr(c::ModelingToolkit.Constant,args...;kwargs...) = c.value
 
 function _build_function(target::StanTarget, eqs, vs, ps, iv,

src/systems/diffeqs/diffeqsystem.jl

@@ -14,7 +14,6 @@ function flatten_differential(O::Operation)
     return (x, t, order + 1)
 end
 
-
 struct DiffEq  # dⁿx/dtⁿ = rhs
     x::Variable
     n::Int

test/build_targets.jl

@@ -25,3 +25,14 @@ eqs = [D(x) ~ a*x - x*y,
 @test ModelingToolkit.build_function(eqs,[x,y],[a],t,target = ModelingToolkit.MATLABTarget()) ==
   """
   diffeqf = @(t,internal_var___u) [internal_var___p(1) * internal_var___u(1) - internal_var___u(1) * internal_var___u(2); -3 * internal_var___u(2) + internal_var___u(1) * internal_var___u(2)];"""
+
+sys = ODESystem(eqs,t,[x,y],[a])
+
+@test ModelingToolkit.build_function(eqs,[x,y],[a],t,target = ModelingToolkit.CTarget()) ==
+      ModelingToolkit.build_function(sys.eqs,[x,y],[a],t,target = ModelingToolkit.CTarget())
+
+@test ModelingToolkit.build_function(eqs,[x,y],[a],t,target = ModelingToolkit.StanTarget()) ==
+      ModelingToolkit.build_function(sys.eqs,[x,y],[a],t,target = ModelingToolkit.StanTarget())
+
+@test ModelingToolkit.build_function(eqs,[x,y],[a],t,target = ModelingToolkit.MATLABTarget()) ==
+      ModelingToolkit.build_function(sys.eqs,[x,y],[a],t,target = ModelingToolkit.MATLABTarget())