plot2d trouble



Hi,

I have two questions concerning plot2d:
1. How do I plot a unit step?
   Using if's together with plot2d doesn't seem to work:
       (C16) plot2d((if (x > 1) then 1 else 0),[x,-1,1]);
       MACSYMA was unable to evaluate the predicate:
       x > 1
        -- an error.  Quitting.  To debug this try DEBUGMODE(TRUE);)
2. The y-range seems to be ignored (e.g. plot2d(x,[x,-1,1],[y,-10,10]) shows
   a plot with a y-range from about -1 to 1). Why is that?

Felix