EDB — 2DN

[2DN] Let $A\subseteq ℝ$ and $f:A\to ℝ$ be a function; let $x\in A$; $f$ is called continuous at $x$ if

$f$ is called continuous if it is continuous in every point.

The set of all continuous functions $f:A\to ℝ$ is denoted with $C(A)$; it is a vector space.