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