I've been trying to come up with a one-variable function that roughly matches this graph:
The closest I've gotten is $ f(d) = \dfrac{\log(c \cdot (1 - \frac{d}{c}))}{\log c} $, but this approaches $y=0$ at $x=c-1$, and steadily declines from $x=0$, instead of sharply.
Are there any functions or tricks I could look into to develop this further?
Thank you.