LinearAlgebra/addmul/mul!(::Matrix{Float64}, ::LinearAlgebra.SymTridiagonal{Int64, V} where V<:AbstractVector{Int64}, ::LinearAlgebra.Symmetric{Float64, S} where S<:(AbstractMatrix{<:Float64}), α, β)/α = 0.4357771157390153, β = false/adjoint and transpose/fa = identity, fb = transpose @test ≈(collect(returned_mat), exp_val, rtol = rtol, atol = atol)