No problem. Yes, it should be an x.
I have absolutely no idea. Probably a necessary part of syntax.
Hmm, I wanted it to be a function of both x and y and then plot it. My u(x,y)
Here is an example they give, from which I've been inspired:
// simple plot using z=f(x,y)
Edit: It seems that x=[0:0.1:12] is a matrix or so. I thought it would plot x from 0 to 12 with increment of 0.1. Sigh. I really have no idea about Scilab.