added: allow C=I in LinModel constructor with 6 args

Author: franckgaga

src/model/linmodel.jl

@@ -14,8 +14,11 @@ struct LinModel{NT<:Real} <: SimModel{NT}
     yop::Vector{NT}
     dop::Vector{NT}
     function LinModel{NT}(A, Bu, C, Bd, Dd, Ts) where {NT<:Real}
-        A, Bu, C = to_mat(A, 1, 1), to_mat(Bu, 1, 1), to_mat(C, 1, 1)
-        nu, nx, ny = size(Bu, 2), size(A, 2), size(C, 1)
+        A, Bu = to_mat(A, 1, 1), to_mat(Bu, 1, 1)
+        nu, nx = size(Bu, 2), size(A, 2)
+        (C == I) && (C = Matrix{NT}(I, nx, nx))
+        C = to_mat(C, 1, 1)
+        ny = size(C, 1)
         Bd = to_mat(Bd, nx, Bd ≠ 0)
         nd = size(Bd, 2)
         Dd = to_mat(Dd, ny, nd)

test/test_sim_model.jl

@@ -73,8 +73,11 @@ Gss2 = c2d(sys_ss[:,1:2], 0.5Ts, :zoh)
     @test isa(linmodel10, LinModel{Float64})
     @test linmodel10.nd == 0
 
-    linmodel11 = LinModel{Float32}(Gss.A, Gss.B, Gss.C, zeros(2, 0), zeros(2, 0), Ts)
-    @test isa(linmodel11, LinModel{Float32})
+    linmodel11 = LinModel(Gss.A, Gss.B, I, 0, 0, Ts)
+    @test linmodel11.ny == linmodel11.nx
+
+    linmodel12 = LinModel{Float32}(Gss.A, Gss.B, Gss.C, zeros(2, 0), zeros(2, 0), Ts)
+    @test isa(linmodel12, LinModel{Float32})
 
 
     @test_throws ErrorException LinModel(sys)