Abstract. Let α be an irrational number and ϕ: ގ → ޒ + be a decreasing sequence tending to zero. Consider the setwhere · denotes the distance to the nearest integer. We show that for general error function ϕ, the Hausdorff dimension of E ϕ (α) depends not only on ϕ, but also heavily on α. However, recall that the Hausdorff dimension of E ϕ (α) is independent of α when ϕ(n) = n −γ with γ > 1.2000 Mathematics Subject Classification. 11J83, 28A80.