Curvature of a semi-log plot

Question

I have the function: $$y=\frac{x(2-x)}{2(1-x)}$$

The semilog plot of this shows a strong knee and a strong elbow feature:

So how do I find where these are?

I have been using this for curvature:

$$\kappa=\frac{y^{\prime\prime}}{(1+y^{\prime 2})^{\frac{3}{2}}}$$

But I'm not getting sensible answers ... is there a better way? How should I account for the semilog plotting? Take the log of the function?

Answer 1

As has been pointed out above, the curvature is an artefact of the plot (scaling) parameters and not a fundamental result.