http://www.walkingrandomly.com/?p=19
I've been trying to find a way to graph this function without buying Mathematica but I haven't found a way. It might be possible with the free online Wolfram Alpha but I haven't succeeded with setting $0<z<0.001$. Any recommendations on how I might be able to get the wished result would be great, with any available program.
Using Wolfram Alpha, simply name the function you wish to plot $z$ and then specify the range for $z$ as well. I plotted your function here:
http://www.wolframalpha.com/input/?i=Plot%5Bz%3DExp%5B-(x%5E2%2By%5E2%2F2)%5DCos%5B4x%5D%2BExp%5B-3((x%2B0.5)%5E2%2By%5E2%2F2)%5D,%7Bx,-3,3%7D,%7By,-5,5%7D,%7Bz,0,0.001%7D%5D