add required name for PDESystem

Author: ChrisRackauckas

src/systems/pde/pdesystem.jl

@@ -56,16 +56,21 @@ struct PDESystem <: ModelingToolkit.AbstractMultivariateSystem
     type: type of the system
     """
     connection_type::Any
+    """
+    name: the name of the system
+    """
+    name::Symbol
     @add_kwonly function PDESystem(eqs, bcs, domain, ivs, dvs,
                                    ps=SciMLBase.NullParameters();
                                    defaults=Dict(),
                                    connection_type = nothing,
                                    checks::Bool = true
+                                   name
                                   )
         if checks
             check_units(eqs)
         end
-        new(eqs, bcs, domain, ivs, dvs, ps, defaults, connection_type)
+        new(eqs, bcs, domain, ivs, dvs, ps, defaults, connection_type, name)
     end
 end
 

test/pde.jl

@@ -12,6 +12,6 @@ bcs = [u(0,x) ~ - x * (x-1) * sin(x),
 domains = [t ∈ (0.0,1.0),
            x ∈ (0.0,1.0)]
 
-pdesys = PDESystem(eq,bcs,domains,[t,x],[u])
+@named pdesys = PDESystem(eq,bcs,domains,[t,x],[u])
 
 @test all(isequal.(independent_variables(pdesys), [t,x]))