From ae72457e5279a609b4250d47a11ba580bce5f693 Mon Sep 17 00:00:00 2001
From: Fredrik Bagge Carlson <baggepinnen@gmail.com>
Date: Fri, 10 Jan 2025 11:43:40 +0100
Subject: [PATCH] QOL improvements for named systems

---
 src/named_systems2.jl       | 27 +++++++++++++++++++++++++++
 test/test_diskmargin.jl     |  8 ++++++--
 test/test_named_systems2.jl | 14 +++++++++++++-
 3 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/src/named_systems2.jl b/src/named_systems2.jl
index 38e3b798..bd5730d4 100644
--- a/src/named_systems2.jl
+++ b/src/named_systems2.jl
@@ -47,6 +47,9 @@ end
 NamedStateSpace(A,B,C,D,x::AbstractVector,u,y,name::String="") = NamedStateSpace{Continuous, StateSpace{Continuous, eltype(A)}}(ss(A,B,C,D), x, u, y, name)
 NamedStateSpace(A,B,C,D,Ts::Number,x,u,y,name::String="") = NamedStateSpace{Discrete{typeof(Ts)}, StateSpace{Discrete{typeof(Ts)}, eltype(A)}}(ss(A,B,C,D,Ts), x, u, y,name)
 
+# This method is used by the basetype(ST)(A, B, C, D, timeevol) construct
+NamedStateSpace(A,B,C,D,te::ControlSystemsBase.TimeEvolution, args...; kwargs...) = named_ss(ss(A,B,C,D,te), args...; kwargs...)
+
 function Base.promote_rule(::Type{U}, ::Type{NamedStateSpace{T, S}}) where
     {T, U<:AbstractStateSpace{T} , S<:AbstractStateSpace{T}} 
     inner = promote_type(U,S)
@@ -70,6 +73,10 @@ function Base.promote_rule(::Type{U}, ::Type{NamedStateSpace{T, S}}) where
     NamedStateSpace{T, inner}
 end
 
+function Base.promote_rule(::Type{NamedStateSpace{TE, StateSpace{TE, T1}}}, ::Type{N}) where {TE, T1, N<:Number}
+    NamedStateSpace{TE, StateSpace{TE, promote_type(T1,N)}}
+end
+
 
 
 function Base.convert(::Type{NamedStateSpace{T, S}}, s::U) where {T, S <: AbstractStateSpace, U <: AbstractStateSpace}
@@ -93,6 +100,12 @@ function Base.convert(::Type{NamedStateSpace{T, S}}, s::U) where {T, S <: Abstra
     named_ss(s2, x = gensym("x"), u = gensym("u"), y = gensym("y"))
 end
 
+function Base.convert(::Type{NamedStateSpace{T, S}}, N::Number) where {T, S <: AbstractStateSpace}
+    te = T <: Discrete ? Discrete(ControlSystemsBase.UNDEF_SAMPLEPETIME) : Continuous()
+    NT = numeric_type(S)
+    named_ss(tf(NT(N), te), x = gensym("x"), u = gensym("u"), y = gensym("y"))
+end
+
 # function Base.convert(::Type{TransferFunction{TE, S}}, s::U) where {TE, S, U <: NamedStateSpace{TE}}
 #     convert(TransferFunction{TE, S}, s.sys)
 # end
@@ -199,6 +212,11 @@ named_ss(G::LTISystem, args...; kwargs...) = named_ss(ss(G), args...; kwargs...)
 
 ControlSystemsBase.ss(sys::NamedStateSpace) = ss(sys.sys)
 
+function ControlSystemsBase.StaticStateSpace(sys::NamedStateSpace) 
+    ssys = StaticStateSpace(sys.sys)
+    named_ss(ssys, sys.name; sys.x, sys.u, sys.y)
+end
+
 iterable(s::Symbol) = [s]
 iterable(v) = v
 
@@ -330,6 +348,15 @@ end
 function Base.:/(s::NamedStateSpace{T, S}, n::Number) where {T <: CS.TimeEvolution, S}
     s*(1/n)
 end
+
+function Base.:/(n::Number, sys::NamedStateSpace)
+    isys = n / sys.sys
+    if isone(n)
+        return named_ss(isys, sys.name*"_inverse", x = sys.x, u = sys.y, y = sys.u)
+    else
+        return named_ss(isys, sys.name*"_scaled_inverse")
+    end
+end
 ##
 
 function Base.hcat(systems::NamedStateSpace{T,S}...) where {T,S}
diff --git a/test/test_diskmargin.jl b/test/test_diskmargin.jl
index 4fdb2163..896c4d1e 100644
--- a/test/test_diskmargin.jl
+++ b/test/test_diskmargin.jl
@@ -1,4 +1,4 @@
-using ControlSystemsBase, RobustAndOptimalControl, MonteCarloMeasurements
+using ControlSystemsBase, RobustAndOptimalControl, MonteCarloMeasurements, Test
 # using RobustAndOptimalControl: bisect_a
 
 # Example from the diskmargin paper
@@ -21,7 +21,11 @@ gainphaseplot(L)
 @test dm.phasemargin == dm.ϕm
 @test :gainmargin ∈ propertynames(dm)
 
-
+dm = diskmargin(named_ss(L), 0)
+@test dm.ω0 ≈ 1.94   atol=0.02
+@test dm.γmin ≈ 0.63    atol=0.02
+@test dm.γmax ≈ 1.59    atol=0.02
+@test dm.α ≈ 0.46   atol=0.02
 
 ## Frequency-dependent margin
 w = exp10.(LinRange(-2, 2, 500))
diff --git a/test/test_named_systems2.jl b/test/test_named_systems2.jl
index 1917d735..52cfb4a2 100644
--- a/test/test_named_systems2.jl
+++ b/test/test_named_systems2.jl
@@ -425,4 +425,16 @@ sys12 = connect(
 
 @test sys12.B[1:2,1] == sys1.B[:, 1]
 @test sys12.B[:,2] == [sys1.B[:, 2]; sys2.B[:, 1]]
-@test sys12.B[3:4,3] == sys2.B[:, 2]
\ No newline at end of file
+@test sys12.B[3:4,3] == sys2.B[:, 2]
+
+## Inv
+s1 = named_ss(ssrand(2,2,2))
+isys = inv(s1)
+@test isys.sys == inv(s1.sys)
+@test isys.x == s1.x
+@test isys.u == s1.y # Names are reversed
+@test isys.y == s1.u
+
+isys = 2/s1
+@test isys.sys == 2/s1.sys
+@test isys.x != s1.x
\ No newline at end of file