Bounded derivative implies uniform continuity: Let I⊆RI\subseteq\mathbb R be an and let f:I→Rf:I\to\mathbb R be on II. If there is a constant MM such that ∣f′(t)∣≤M|f'(t)|\le M for all t∈It\in I, then for all x,y∈Ix,y\in I,

∣f(x)−f(y)∣≤M∣x−y∣.|f(x)-f(y)|\le M|x-y|.

Consequently, ff is Lipschitz and in particular uniformly continuous on II.

Remarks

This estimate is a direct application of the . It is the one-dimensional special case of the for differentiable maps.