fix #1020 (#1021)

* fix #1020

* relax

Author: baggepinnen

Project.toml

@@ -2,11 +2,12 @@ name = "ControlSystems"
 uuid = "a6e380b2-a6ca-5380-bf3e-84a91bcd477e"
 authors = ["Dept. Automatic Control, Lund University"]
 repo = "https://github.com/JuliaControl/ControlSystems.jl.git"
-version = "1.15.0"
+version = "1.15.1"
 
 [deps]
 ControlSystemsBase = "aaaaaaaa-a6ca-5380-bf3e-84a91bcd477e"
 DelayDiffEq = "bcd4f6db-9728-5f36-b5f7-82caef46ccdb"
+DiffEqBase = "2b5f629d-d688-5b77-993f-72d75c75574e"
 DiffEqCallbacks = "459566f4-90b8-5000-8ac3-15dfb0a30def"
 ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
@@ -22,6 +23,7 @@ StaticArrays = "90137ffa-7385-5640-81b9-e52037218182"
 Aqua = "0.5"
 ControlSystemsBase = "1.3"
 DelayDiffEq = "5.31"
+DiffEqBase = "6"
 DiffEqCallbacks = "2.16, 3, 4"
 ForwardDiff = "0.10, 1"
 OrdinaryDiffEq = "6.60"

src/ControlSystems.jl

@@ -3,6 +3,7 @@ module ControlSystems
 using Reexport
 @reexport using ControlSystemsBase
 using ControlSystemsBase: issiso, ninputs, noutputs, nstates, numeric_type
+import DiffEqBase
 
 
 using LinearAlgebra

src/timeresp.jl

@@ -1,4 +1,4 @@
-import OrdinaryDiffEq: ODEProblem, Tsit5, DiffEqBase, solve, BS3
+import OrdinaryDiffEq: ODEProblem, Tsit5, solve, BS3
 import ControlSystemsBase: lsim, step, impulse, HammersteinWienerSystem, DelayLtiSystem, PartitionedStateSpace, SimResult
 import DelayDiffEq: MethodOfSteps
 # Function for DifferentialEquations lsim