[pstricks] pspicture(x1,x2)(y1,y2)

[Paolo Covelli]

Hi all, 

I'm problems tu use coordinates (x1,x2)(y1,y2) in environment:

\begin{pspicture}(x1,x2)(y1,y2)
  "PSTricks code"
\end{pspicture}

which are their purpose ?

For example: (-7,-4)(7,4) what is?

If I wish a centered image, how do I it?

Thanks in advance.

Paolo.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://tug.org/pipermail/pstricks/attachments/20080526/940ba282/attachment.html