[Math] examples of first strictly concave then convex function

functions

I want to find out a continuous function on $[0,L]$, $L$ is a positive number, which looks like this red curve:

wanted shape

The function is always positive.

This function firstly is strictly concave, then the function is strictly convex. Moreover, like the graph shows, this function increases rapidly first and then increases very slowly and then increases very quickly.

But I can not come up one such function. Can you help to find out a very simple continuous function to satisfy this graph ? Thank you!

Best Answer

$f(x) = x^3 \qquad g(x) = x^5 \qquad h(x)=e^x-1/2x^2-1$ If you want to move the function to right just put $x=t-c$ where $0<c<L$