Add get_noiseeqs

Author: YingboMa

docs/src/systems/AbstractSystem.md

@@ -34,6 +34,7 @@ Optionally, a system could have:
   condition.
 - `get_default_p(sys)`: A `Dict` that maps parameters into their default value.
 - `independent_variable(sys)`: The independent variable of a system.
+- `get_noiseeqs(sys)`: Noise equations of the current-level system.
 
 Note that there's `get_iv(sys)`, but it is not advised to use, since it errors
 when the system has no field `iv`. `independent_variable(sys)` returns `nothing`

src/systems/abstractsystem.jl

@@ -134,7 +134,22 @@ function structure(sys::AbstractSystem)
     s isa SystemStructure || throw(ArgumentError("SystemStructure is not yet initialized, please run `sys = initialize_system_structure(sys)` or `sys = alias_elimination(sys)`."))
     return s
 end
-for prop in [:eqs, :iv, :states, :ps, :default_p, :default_u0, :observed, :tgrad, :jac, :Wfact, :Wfact_t, :systems, :structure]
+for prop in [
+             :eqs
+             :noiseeqs
+             :iv
+             :states
+             :ps
+             :default_p
+             :default_u0
+             :observed
+             :tgrad
+             :jac
+             :Wfact
+             :Wfact_t
+             :systems
+             :structure
+            ]
     fname1 = Symbol(:get_, prop)
     fname2 = Symbol(:has_, prop)
     @eval begin