From f68bf1cfa3071f39df7fbd18a117789f4aef720f Mon Sep 17 00:00:00 2001
From: Fredrik Bagge Carlson <baggepinnen@gmail.com>
Date: Thu, 16 Jan 2025 13:11:36 +0100
Subject: [PATCH] avoid some type issues arising with Symbolics

`D` was reshaped without need, resulting in a reshapearray which leads to downstream inference problems
---
 lib/ControlSystemsBase/src/types/StateSpace.jl | 5 ++---
 lib/ControlSystemsBase/src/types/conversion.jl | 3 ++-
 lib/ControlSystemsBase/src/types/zpk.jl        | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/lib/ControlSystemsBase/src/types/StateSpace.jl b/lib/ControlSystemsBase/src/types/StateSpace.jl
index 50ba042eb..a58967956 100644
--- a/lib/ControlSystemsBase/src/types/StateSpace.jl
+++ b/lib/ControlSystemsBase/src/types/StateSpace.jl
@@ -113,14 +113,13 @@ function StateSpace(D::AbstractArray{T}, timeevol::TimeEvolution) where {T<:Numb
     A = zeros(T, 0, 0)
     B = zeros(T, 0, nu)
     C = zeros(T, ny, 0)
-    D = reshape(D, (ny,nu))
     return StateSpace(A, B, C, D, timeevol)
 end
 StateSpace(D::AbstractArray, Ts::Number) = StateSpace(D, Discrete(Ts))
 StateSpace(D::AbstractArray) = StateSpace(D, Continuous())
 
-StateSpace(d::Number, Ts::Number; kwargs...) = StateSpace([d], Discrete(Ts))
-StateSpace(d::Number; kwargs...) = StateSpace([d], Continuous())
+StateSpace(d::Number, Ts::Number; kwargs...) = StateSpace([d;;], Discrete(Ts))
+StateSpace(d::Number; kwargs...) = StateSpace([d;;], Continuous())
 
 
 # StateSpace(sys) converts to StateSpace
diff --git a/lib/ControlSystemsBase/src/types/conversion.jl b/lib/ControlSystemsBase/src/types/conversion.jl
index 0eb8cc5c0..c43808f2c 100644
--- a/lib/ControlSystemsBase/src/types/conversion.jl
+++ b/lib/ControlSystemsBase/src/types/conversion.jl
@@ -82,7 +82,8 @@ Base.convert(::Type{StateSpace}, s::HeteroStateSpace) = StateSpace(s.A, s.B, s.C
 Base.convert(::Type{StateSpace}, s::HeteroStateSpace{Continuous}) = StateSpace(s.A, s.B, s.C, s.D)
 
 function Base.convert(::Type{StateSpace}, G::TransferFunction{TE,<:SisoTf{T0}}; kwargs...) where {TE,T0<:Number}
-    T = Base.promote_op(/,T0,T0)
+    ONE = one(T0)
+    T = typeof(ONE/ONE)
     convert(StateSpace{TE,T}, G; kwargs...)
 end
 
diff --git a/lib/ControlSystemsBase/src/types/zpk.jl b/lib/ControlSystemsBase/src/types/zpk.jl
index 70d8792ec..50bb77bcc 100644
--- a/lib/ControlSystemsBase/src/types/zpk.jl
+++ b/lib/ControlSystemsBase/src/types/zpk.jl
@@ -69,8 +69,8 @@ function zpk(G::TransferFunction{TE,S}) where {TE<:TimeEvolution,T0, S<:SisoTf{T
     convert(TransferFunction{TE,SisoZpk{T, complex(T)}}, G)
 end
 
-zpk(var::AbstractString) = zpk(tf(var))
-zpk(var::AbstractString, Ts::Real) = zpk(tf(var, Ts))
+zpk(var::Union{AbstractString, Char}) = zpk(tf(var))
+zpk(var::Union{AbstractString, Char}, Ts::Real) = zpk(tf(var, Ts))
 
 # Catch all 3(4) argument versions
 zpk(z, p, k, Ts::Number) = zpk(z, p, k, Discrete(Ts))