Re: L-shape function - Turning point?



On Sat, 1 Oct 2005, kwokcalvin@xxxxxxx wrote:

> I have a strictly increasing smooth "L-shape" function. At the point
where the function bends, the 2nd derivative reaches its maximum. I want
to know if there is a mathematical name for this particular point?
>
> Can I still call it a turning point?
>
As long as you inform the reader about your choice of terminology,
why not? (And I have heard the expression "elbow", too, although I do not
know how widely it is accepted.)

From geometry, a point where the curvature reaches its extremum is called
a vertex. And the second derivative is approximately the curvature if the
graph is flat enough. So, there is a possibility to call your turning
point the "linearized vertex", but why bother, because it sounds
cumbersome.

Cheers, ZVK(Slavek).
.