Quite simply, I need a function that will produce a graph similar to the one below. Important to note:
1) Y switches from negative to positive at X=1/3
2) Y ranges from -0.1 to +0.1, not to and from infinity
3) Y should be very close to 0 by X=1/6 and X=3/6.
4) It should have curves similar to those in the picture (Mod note: the original image link is dead, for context I'm replacing it with the graph of the function given in the accepted answer.)
A massive thank-you to whomever can figure this one out.