Two-scale limits #
This file packages the ε → 0 first, truncation order B → ∞ second
argument used in paper (3.39).
theorem
Anderson4D.tendsto_of_two_scale_approximation
{ι : Type u_1}
{E : Type u_2}
[PseudoMetricSpace E]
{l : Filter ι}
(f : ι → E)
(g : ℕ → ι → E)
(zB : ℕ → E)
(z : E)
(error : ℕ → ℝ)
(hg : ∀ (B : ℕ), Filter.Tendsto (g B) l (nhds (zB B)))
(hz : Filter.Tendsto zB Filter.atTop (nhds z))
(herror : Filter.Tendsto error Filter.atTop (nhds 0))
(hclose : ∀ (B : ℕ), ∀ᶠ (i : ι) in l, dist (f i) (g B i) ≤ error B)
:
Filter.Tendsto f l (nhds z)
A family converges if it is uniformly approximated, at every fixed truncation order, by families with known limits; the approximation error and those limits then converge as the truncation order tends to infinity.
No countability or nontriviality assumption on the primary filter is needed.