changed: preparestate! for SimModel now receives no additional arg.

The old method with `ym` and `d` arguments still works but it's now deprecated.

The old method was not making sense since the two arguments were simply ignored. Moreover, it's now consistent with the `updatestate!` function, that is, it receive no measurement arguments for `SimModel`.

Author: franckgaga

src/sim_model.jl

@@ -208,11 +208,17 @@ function initstate!(model::SimModel, u, d=model.buffer.empty)
 end
 
 @doc raw"""
-    preparestate!(model::SimModel, _ , _ ) -> x
+    preparestate!(model::SimModel) -> x
 
 Do nothing for [`SimModel`](@ref) and return the current model state ``\mathbf{x}(k)``. 
 """
-function preparestate!(model::SimModel, ::Any , ::Any=model.buffer.empty)
+function preparestate!(model::SimModel)
+    x  = model.buffer.x
+    x .= model.x0 .+ model.xop
+    return x 
+end
+
+@deprecate function preparestate!(model::SimModel, ::Any , ::Any=model.buffer.empty)
     x  = model.buffer.x
     x .= model.x0 .+ model.xop
     return x 

test/1_test_sim_model.jl

@@ -107,7 +107,8 @@ end
     @test evaloutput(linmodel1, Float64[]) ≈ linmodel1(Float64[]) ≈ [50,30]
     x = initstate!(linmodel1, [10, 60])
     @test evaloutput(linmodel1) ≈ [50 + 19.0, 30 + 7.4]
-    @test preparestate!(linmodel1, [10, 60]) ≈ x
+    @test preparestate!(linmodel1) ≈ x           # new method
+    @test preparestate!(linmodel1, [10, 60]) ≈ x # deprecated method
     @test updatestate!(linmodel1,  [10, 60]) ≈ x
     linmodel2 = LinModel(append(tf(1, [1, 0]), tf(2, [10, 1])), 1.0)
     x = initstate!(linmodel2, [10, 3])