power to a power

[FireTime]

*flash8
*actionscript2

I've been having problems with this math command

this._xscale = ((2.71828)^(-(this._x-120)/100)^2)+1;
this._yscale = this._xscale;

that it does as the symbols ._x approaches 120 it's scale increases.
When i graph out this function i get the results i want a nice bell shaped curve that increases at 120 to a value of 2 and sloops down to 1 around ~300.

after experimenting with flash it appears that it doesn't like power raised to a power such as 2^2^2 or 2^(2^2).

Anyone have any ideas?

if you would like to see what the graph looks like enter
(2.71828)^(-((x-120)/100)^2)+1
into Java Grapher
note: change Xmax to 500