I recently learned that I can plot a function f(x) as follows.

```
using Plots
f(x) = 1/(1+exp(-x))
scatter(f, (-10.0,10.0)...)
```

And, I noticed that the plot is not evenly spaced with respect to the x-axis when plotted with a scatter as shown in the figure. There are more points clustered where the curve is steeper and fewer points where it is less varied. There seems to be some kind of mathematical intelligence behind it.

How are the x coordinates of each of these points being generated?

Is there a function that returns such an unevenly spaced x coordinates when given f(x)?