Specific function needed

Hello, I'm looking for a function f(x) which is 0 when x is 0, has a maximum of 1 at an x of my choosing, and goes to 0 as x goes to infinity. A lot like a weibull function, but I want to control the position and value of the maximum. Any ideas (function is only for x>=0)?

Thanks.

This is very simple if you don't want any differentiability conditions. Do you? If so, what conditions?

Well, I just need a differentiable function, but I have no constraints on the differentiation. I just need 0 at 0 and infinity and a controllable maximum.

Thanks.

Looks like I found it.