diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index e7182d26..5dd8e86f 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -1,39 +1,24 @@
 name: CI
-on:
-  - pull_request
+on: [push]
 jobs:
   test:
-    name: Julia ${{ matrix.version }} - ${{ matrix.os }} - ${{ matrix.arch }} - ${{ github.event_name }}
     runs-on: ${{ matrix.os }}
     strategy:
-      fail-fast: false
       matrix:
-        version:
-          - '1.10'
-        os:
-          - ubuntu-latest
-        arch:
-          - x64
+        julia-version: ['1.10']
+        os: [ubuntu-latest]
     steps:
       - uses: actions/checkout@v2
-      - uses: julia-actions/setup-julia@v1
+      - uses: julia-actions/setup-julia@latest
         with:
-          version: ${{ matrix.version }}
-          arch: ${{ matrix.arch }}
-      - uses: actions/cache@v1
-        env:
-          cache-name: cache-artifacts
-        with:
-          path: ~/.julia/artifacts
-          key: ${{ runner.os }}-test-${{ env.cache-name }}-${{ hashFiles('**/Project.toml') }}
-          restore-keys: |
-            ${{ runner.os }}-test-${{ env.cache-name }}-
-            ${{ runner.os }}-test-
-            ${{ runner.os }}-
-      - uses: julia-actions/julia-buildpkg@v1
-      - uses: julia-actions/julia-runtest@v1
+          version: ${{ matrix.julia-version }}
+      - uses: julia-actions/cache@v1
+      - uses: julia-actions/julia-runtest@latest
       - uses: julia-actions/julia-processcoverage@v1
       - uses: codecov/codecov-action@v4
         with:
-          file: lcov.info
+          file: ./lcov.info
+          flags: unittests
+          name: codecov-umbrella
+          fail_ci_if_error: false
           token: ${{ secrets.CODECOV_TOKEN }}
diff --git a/src/canonical.jl b/src/canonical.jl
index 73deacec..c76d0d65 100644
--- a/src/canonical.jl
+++ b/src/canonical.jl
@@ -76,6 +76,8 @@ If `C1`, then an additional convention for SISO systems is used, that the `C`-ma
 
 `E` is an eigen factorization of `A`.
 
+The modal form makes apparent which modes are controllable from which inputs, and which are observable from which outputs. Non-minimal realizations may trigger singularity exceptions.
+
 See also [`hess_form`](@ref) and [`schur_form`](@ref)
 """
 function modal_form(sys; C1 = false)
diff --git a/src/find_lft.jl b/src/find_lft.jl
index b67a2f12..1a4964e5 100644
--- a/src/find_lft.jl
+++ b/src/find_lft.jl
@@ -95,7 +95,7 @@ function find_lft(sys::StateSpace{<:Any, <:AbstractParticles{<:Any, N}}, delta,
             iterations        = 40000,
             allow_f_increases = true,
             time_limit        = 45,
-            x_tol             = 1e-8,
+            x_abstol          = 1e-8,
             f_reltol          = 0,
             g_tol             = 1e-16,
         ),
diff --git a/src/mimo_diskmargin.jl b/src/mimo_diskmargin.jl
index a8b01f07..e665303c 100644
--- a/src/mimo_diskmargin.jl
+++ b/src/mimo_diskmargin.jl
@@ -176,7 +176,7 @@ function structured_singular_value(M::AbstractArray{T}; tol=1e-4, scalings=false
         iterations        = 1000,
         allow_f_increases = false,
         time_limit        = 100,
-        x_tol             = 0,
+        x_abstol          = 0,
         f_abstol          = 0,
         g_tol             = tol,
         f_calls_limit     = 0,
@@ -400,7 +400,7 @@ function loop_scaling(M::Matrix, tol=1e-4)
         iterations        = 1000,
         allow_f_increases = false,
         time_limit        = 100,
-        x_tol             = 0,
+        x_abstol          = 0,
         f_abstol          = 0,
         g_tol             = tol,
         f_calls_limit     = 0,
@@ -458,7 +458,7 @@ end
 #         iterations        = 1000,
 #         allow_f_increases = false,
 #         time_limit        = 100,
-#         x_tol             = 0,
+#         x_abstol          = 0,
 #         f_abstol          = 0,
 #         g_tol             = tol,
 #         f_calls_limit     = 0,
diff --git a/src/uncertainty_interface.jl b/src/uncertainty_interface.jl
index 48d8f8f4..e07133bd 100644
--- a/src/uncertainty_interface.jl
+++ b/src/uncertainty_interface.jl
@@ -459,6 +459,10 @@ end
 #     Complex(StaticParticles(getfield.(parts, :re)), StaticParticles(getfield.(parts, :im)))
 # end
 
+function ControlSystemsBase.poles(G::TransferFunction{<:ControlSystemsBase.TimeEvolution, ControlSystemsBase.SisoRational{T}}) where T <: AbstractParticles
+    poles(ss(G))
+end
+
 function ControlSystemsBase.tzeros(A::AbstractMatrix{T}, B::AbstractMatrix{T}, C::AbstractMatrix{T}, D::AbstractMatrix{T}) where T <: AbstractParticles
     bymap(tzeros, A, B, C, D)
 end
diff --git a/test/test_hinfgrad.jl b/test/test_hinfgrad.jl
index 4d0210bd..f5e81e8a 100644
--- a/test/test_hinfgrad.jl
+++ b/test/test_hinfgrad.jl
@@ -78,7 +78,7 @@ v = vec(C)
 #         iterations        = 1000,
 #         allow_f_increases = false,
 #         time_limit        = 1,
-#         x_tol             = 0,
+#         x_abstol          = 0,
 #         f_abstol          = 0,
 #         g_tol             = 1e-8,
 #         f_calls_limit     = 0,
diff --git a/test/test_uncertainty.jl b/test/test_uncertainty.jl
index da8e5556..abe33b0b 100644
--- a/test/test_uncertainty.jl
+++ b/test/test_uncertainty.jl
@@ -1,4 +1,4 @@
-using RobustAndOptimalControl, ControlSystemsBase, MonteCarloMeasurements, Test
+using RobustAndOptimalControl, ControlSystemsBase, MonteCarloMeasurements, Test, LinearAlgebra
 
 d = δr()
 @test d.val == 0
@@ -387,4 +387,17 @@ using SparseArrays
 @test MOP.nx == P.nx*N
 @test MOP.nu == P.nu
 
-@test MOP.A isa SparseMatrixCSC
\ No newline at end of file
+@test MOP.A isa SparseMatrixCSC
+
+
+## Poles and zeros of tf
+
+ω = 4..12
+ζ = 0.054..0.084
+
+P  = tf([2*ζ/ω, 1],  [1/ω^2, 2*ζ/ω, 1, 0, 0])
+
+C = 1.0 * tf([1, 1], [0.1, 1])
+G = feedback(C*P, 1)
+poles(G)
+tzeros(G)
\ No newline at end of file