# Looking for a function that produces the illustrated graph

I'm looking for a function that creates the blue curve shown in the picture. The point is that within a certain range (e.g. x=0 to x=0.8) the output of the function should be relatively close to 1.0. If possible it would be exactly 1 but "close" to 1 (within 10% or so) would be good enough. However, the first value produced by the function should be exactly 1. eventually, the output should drop sharply to y=0.

The available input value is x which linearly increases along the x-axis from 0 to 1. The function could rely on any other parameter necessary to achieve the illustrated curve.

Any ideas?

• Try $y=(1-x^n)^{1/n}$ for, say, $n>8$. – g.kov Apr 27 at 10:03

\begin{align} y(x)&=(1-x^n)^{1/n} . \end{align}
This is how the graph of this function looks for $$n=5\dots12$$:
$$x^{2n} + y^{2n} = 1$$ As $$n$$ gets bigger and bigger, its shape resembles a square! For your purpose I would think $$n=4$$ and $$n=6$$ are good choices.