Bernstein polynomial: function to approximate

Question

I am studying the Bernstein polynomial with Matlab. I wish to code the example in the wikipedia page of Bernstein polynomial, but I can not figure out the explicit form of the red function (see figure).

Answer 1

Is impossible figure out the explicit formula of the red function using only a picture of its graph. However, this description says:

This animation was created with Maple 9.5 and Jasc Animation Shop. It shows Bernstein polynomials approximating $x \sin(\frac 72\pi {\sqrt {x}})$ (chosen for purely aesthetic reasons).

Although, it appears that the true formula is $-x \sin(\frac 72\pi {\sqrt {x}})$.