OMG i'm clearing out some old files and i came across an equation i jotted down. Based on other writings on this note, i'm guessing it's about 10 years old. I know immediately what it's is modelling. But you'll have to find the function and software to draw it. In 1994 i was using software called Derive.

Here it is in MathML using content markup (ie. not presentation markup).

Unfortunately i just read here that neither Firefox nor Amaya support content markup.

What's the difference between the markups? One makes it easy for non-mathematicians to present mathematical expressions. The other, content, is intended to capture the sematics of math.