diff --git a/src/BallAndBeam.jl b/src/BallAndBeam.jl
index 33dc2ced3bcf9ec1b0d4a8a993f0acbf21769cf4..2d185fd95d9151d853c354674aa26dc53e641e91 100644
--- a/src/BallAndBeam.jl
+++ b/src/BallAndBeam.jl
@@ -16,7 +16,7 @@ module BallAndBeam
 
 export run_experiment, fra, sortfqs,
 bopl, bopl!, nypl, nypl!, plot, fbdesign, ffdesign, opendoc
-export SysFilter, init_sysfilter, sysfilter!, run_control_2DOF # For documentation
+export SysFilter, run_control_2DOF # For documentation
 
 
 using LabProcesses, Plots, Polynomials, ControlSystems, ProgressMeter
@@ -139,7 +139,7 @@ nypl(G; kwargs...) = (plot();nypl!(G;kwargs...))
 	sysFB,L,T,C = fbdesign(G::AbstractMatrix, polevect, zerovect, gain)
 Frequency Compensation to determine polynominals in compensator C=S/R.
 Frequency responses for loop transfer, closed loop and controller are calculated.
-`sys` is of type `StateSpace`, to be used together with [`sysfilter!`](@ref)
+`sys` is of type `StateSpace`, to be used together with [`SysFilter!`](@ref)
 `G` is a frequency response matrix with ω in the first column and G(iω) in the second.
 """
 function fbdesign(G::AbstractMatrix, polevect, zerovect, gain)
@@ -156,7 +156,7 @@ end
 	sysFF,YR,FF = ffdesign(G, polevect, zerovect, gain)
 Feedforward filter BFF/AFF to shape transfer function from `r` to `y`.
 Frequency responses for closed loop with FF-filter and FF-filter are calculated.
-`sys` is of type `StateSpace`, to be used together with [`sysfilter!`](@ref)
+`sys` is of type `StateSpace`, to be used together with [`SysFilter!`](@ref)
 """
 function ffdesign(G, polevect, zerovect, gain)
 	sysFF,YR,_,FF = fbdesign(G, polevect, zerovect, gain)
@@ -179,24 +179,13 @@ function opendoc()
 	run(`xdg-open $docpath`)
 end
 
-"""
-	state = init_sysfilter(sys::StateSpace)
-Use together with [`sysfilter!`](@ref)
-"""
-init_sysfilter
-
-"""
-	output = sysfilter!(state, sys::StateSpace, input)
-Returns the filtered output `y` in `y = Cx+Du, x'=Ax+Bu`
-
-This function is used to implement control loops where a signal is filtered through a
-dynamical system, i.e., `U(z) = C(z)E(z)`. Initialize `state` using [`init_sysfilter`](@ref).
-"""
-sysfilter!
 
 """
-	sf = SysFilter(sys::StateSpace)
-Create a SysFilter object that can be used to implement control loops and simulators with LTI systems, i.e., `U(z) = C(z)E(z)`. See [`sysfilter!`](@ref) for usage.
+	Csf = SysFilter(sys::StateSpace)
+Returns an object used for filtering signals through LTI systems.
+Create a SysFilter object that can be used to implement control loops and simulators
+with LTI systems, i.e., `U(z) = C(z)E(z)`. To filter a signal `u` through the filter,
+call like `y = Csf(u)`. Calculates the filtered output `y` in `y = Cx+Du, x'=Ax+Bu`
 """
 SysFilter
 
diff --git a/src/arx.jl b/src/arx.jl
index f670c20b1cff6404fc73c6b4410215234457986f..5eecff1bb446b67e8cb6300696eccd17358670f8 100644
--- a/src/arx.jl
+++ b/src/arx.jl
@@ -86,10 +86,8 @@ function arx(h,y::AbstractVector{Float64}, u::AbstractVector{Float64}, na, nb; 
 
     if λ == 0
         w = A\y_train
-        method = :LS
     else
         w = (A'A + λ*eye(size(A,2)))\A'y_train
-        method = :LS_reg
     end
 
     a = [1; -w[1:na]]