Merge pull request #810 from SciML/isautonomous

add isautonomous

Author: YingboMa

Project.toml

@@ -1,7 +1,7 @@
 name = "ModelingToolkit"
 uuid = "961ee093-0014-501f-94e3-6117800e7a78"
 authors = ["Chris Rackauckas <accounts@chrisrackauckas.com>"]
-version = "5.6.4"
+version = "5.7.0"
 
 [deps]
 ArrayInterface = "4fba245c-0d91-5ea0-9b3e-6abc04ee57a9"

src/systems/diffeqs/abstractodesystem.jl

@@ -99,6 +99,11 @@ jacobian_sparsity(sys::AbstractODESystem) =
     jacobian_sparsity([eq.rhs for eq ∈ equations(sys)],
                       [dv for dv in states(sys)])
 
+function isautonomous(sys::AbstractODESystem)
+    tgrad = calculate_tgrad(sys;simplify=true)
+    all(iszero,tgrad)
+end
+
 function DiffEqBase.ODEFunction(sys::AbstractODESystem, args...; kwargs...)
     ODEFunction{true}(sys, args...; kwargs...)
 end
@@ -198,7 +203,7 @@ function ODEFunctionExpr{iip}(sys::AbstractODESystem, dvs = states(sys),
       $fsym(u,p,t) = $f_oop(u,p,t)
       $fsym(du,u,p,t) = $f_iip(du,u,p,t)
     end
-  
+
     tgradsym = gensym(:tgrad)
     if tgrad
         tgrad_oop, tgrad_iip = generate_tgrad(sys, dvs, ps;

test/odesystem.jl

@@ -243,6 +243,7 @@ sys = ODESystem(eqs)
 @test all(isequal.(states(sys), [x, y, z]))
 @test all(isequal.(parameters(sys), [σ, β]))
 @test equations(sys) == eqs
+@test ModelingToolkit.isautonomous(sys)
 
 # issue 701
 using ModelingToolkit