Is there a function $f:R\to R$ that satisfies
$f$ is everywhere discontinuous.
$\lim_{h \to 0}(f(a+h)-f(a-h))=0$ for all $a \in R$
Is there a function $f:R\to R$ that satisfies
$f$ is everywhere discontinuous.
$\lim_{h \to 0}(f(a+h)-f(a-h))=0$ for all $a \in R$