[Maxima] Argh, why can't I ever figure out plot2d/find_root/etc

[dlakelan]

whenever I try to use Maxima for numerical calculations with functions, 
rather than expressions, it just doesn't work.

Oh sure, maybe calling my function Moment(.001,d) at the command line 
works fine, but when I do plot2d(Moment(phi,d),[phi,0,.001]) (with "d" 
bound at the global level), I get some stupid error related to how I'm 
using find_root deep inside this function...

Why does this suck so much?