LinearAlgebra/addmul/mul!(::Matrix{Int64}, ::LinearAlgebra.Tridiagonal{Int64, V} where V<:AbstractVector{Int64}, ::LinearAlgebra.LowerTriangular{Int64, S} where S<:AbstractMatrix{Int64}, α, β)/α = -4, β = false/adjoint and transpose/fa = identity, fb = adjoint @test ≈(collect(returned_mat), exp_val, rtol = rtol, atol = atol)