Nowhere continuous function: Difference between revisions

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In [[mathematics]], a '''nowhere continuous''' [[function (mathematics)|function]], also called an '''everywhere discontinuous''' function, is a function that is not [[continuous]] at any point of its [[function ___domain (mathematics)|___domain]]. If ''f'' is a function from [[real number]]s to real numbers, then ''f''(''x'') is nowhere continuous if for each point ''x'' there is an ''&epsilon;''>0 such that for each ''&delta;''>0 we can find a point ''y'' such that |''x''&minus;''y''|<''&delta;'' and |''f''(''x'')&minus;''f''(''y'')|&ge;''&epsilon;''. The import of this statement is that no matter how close we get to any fixed point, there are nearby points at which the function takes not-nearby values.
 
More general definitions of this kind of function can be obtained, by replacing the [[absolute value]] by the distance function in a [[metric space]], or the continuity definition by the definition of continuity in a [[topological space]].