"trigrat" caught in infinite loop - depending on how you call it



On 11/15/2012 03:23 AM, Barton Willis wrote:
>    (%i2) e : 2*x/(sqrt(y)+x) - (x^2/((sqrt(y)+x)^2));
>    (%o2) (2*x)/(sqrt(y)+x)-x^2/(sqrt(y)+x)^2
>
>    (%i3) ( trigrat(e), trigrat(xthru(e)));
>       << Expression too long to display! >>
>
> to finish, but the result is a ridiculously large mess (didn't attempt to check if it is correct).
I didn't attempt it either, but
  plot3d(e,[x,-5,5],[y,-5,5],[z,-1000,1000],[grid,60,60]);
and
  plot3d(trigrat(e),[x,-5,5],[y,-5,5],[z,-1000,1000],[grid,60,60]);

show similar plots, except from a couple of wholes near (x,y)=(3,1) and 
(2,4).

Regards,
Jaime