Does there exist a function that is differentiable but not integrable? or integrable but not differentiable?
It has become very complicated to me to find out a function which is differentiable but not integrable or integrable but not differentiable.
Solution 1:
A low level answer:
Differentiable Function that is not Integrable:
$f(x)=\frac{1}{x}$ is differentiable in $(0,1)$, however it's not integrable in this interval.
$$\int_{0}^{1} f(x) \mathrm dx=\int_{0}^{1} \frac{1}{x} \mathrm dx$$
$$=\ln 1- \ln 0$$
That's Undefined.
Integrable but Not-Differentiable
Weierstrass Function (Repeating what already answered).
Solution 2:
Well, If you are thinking Riemann integrable, Then every differentiable function is continuous and then integrable!
However any bounded function with discontinuity in a single point is integrable but of course it is not differentiable!