Load ApproxFun in tests.

Project.toml

@@ -23,6 +23,7 @@ ApproxFun = "28f2ccd6-bb30-5033-b560-165f7b14dc2f"
 FourierApproxExt = "ApproxFun"
 
 [extras]
+ApproxFun = "28f2ccd6-bb30-5033-b560-165f7b14dc2f"
 Bessels = "0e736298-9ec6-45e8-9647-e4fc86a2fe38"
 MatrixPencils = "48965c70-4690-11ea-1f13-43a2532b2fa8"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
@@ -46,4 +47,4 @@ julia = "1.10"
 
 
 [targets]
-test = ["Bessels","MatrixPencils","Test"]
+test = ["ApproxFun","Bessels","MatrixPencils","Test"]

src/psfutils.jl

@@ -1154,6 +1154,7 @@ function psordschur!(S::AbstractVector{Matrix{Float64}}, Z::AbstractVector{Matri
    rev || (reverse!(m); reverse!(n))
    ldq = rev ? n : [m[end];m[1:end-1]]
    nc = minimum(n)
+   nc == length(select) || throw(ArgumentError("Dimension of select must be equal to the number of core eigenvalues $nc"))
    kschur = rev ? schurindex : k-schurindex+1
    ni = zeros(Int,k)
    s = ones(Int,k)
@@ -1195,6 +1196,7 @@ function psordschur1!(S::AbstractVector{Matrix{Float64}}, Z::AbstractVector{Matr
    (all(m .== nc) && all(n .== nc)) || error("all elements of S must be square matrices of same dimension")
    k == length(Z) || error("S and Z must have the same length")
    (all(size.(Z,1) .== nc) && all(size.(Z,2) .== nc)) || error("all elements of Z must be square matrices of same dimension as S")
+   nc == length(select) || throw(ArgumentError("Dimension of select must be equal to the number of core eigenvalues $nc"))
    kschur = rev ? schurindex : k-schurindex+1
    ni = zeros(Int,k)
    s = ones(Int,k)

test/test_pmutils.jl

@@ -1,8 +1,8 @@
 module Test_pmutils
 
+using PeriodicMatrices
 using ApproxFun
 using Symbolics
-using PeriodicMatrices
 using Test
 using LinearAlgebra
 using MatrixPencils

test/test_pschur.jl

@@ -1,6 +1,7 @@
 module Test_pschur
 
 using PeriodicMatrices
+using ApproxFun
 using Test
 using LinearAlgebra
 using LinearAlgebra: BlasInt
@@ -452,17 +453,17 @@ A3 = [-4 3 5 2 2; 2 -5 -2 0 2; -1 -2 5 3 0; 0 1 -3 -5 0; 0 0 4 -4 3];
 
 A = [A1, A2, A3];
 @time S, Z, eigs, ischur, α, γ = pschur(A; rev = true);
-select =  (real(eigs) .< 0)[1:3]
+select =  (real(eigs) .< 0)
 @time psordschur!(S,Z,select; schurindex=ischur, rev = true)  
 @test check_psim(A,Z,S; rev = true)  
 ev=MatrixPencils.ordeigvals(S[3]*S[2]*S[1])  
 
 @time S, Z, eigs, ischur, α, γ = pschur(A; rev = true);
-select =  (real(eigs) .< 0)[1:3]
+select =  (real(eigs) .< 0)
 @time psordschur1!(S,Z,select; schurindex=ischur, rev = true)  
 @test check_psim(A,Z,S; rev = true)  
 ev1=MatrixPencils.ordeigvals(S[3]*S[2]*S[1])  
-@test ev ≈ ev1
+@test sort(ev) ≈ sort(ev1)
 
 
 # Example Hench & Laub IEETAC 1994