Polar Stereographic projection Extent

[Vincent J. Troisi]

Ryan Ollerenshaw wrote:
> I am having a bit of trouble figuring out the extent I should use to 
> display the entire northern hemisphere using the Polar Stereographic 
> projection.  The best that i have been able to come up with is:
>
> EXTENT 3000 2000 4000000 3000000
>
> but this only displays the right half of the norther hemisphere, how 
> can i display the full 360 degrees of the northern hemisphere all at 
> one time?  When using a polar projection i am not sure what the extent 
> numbers actually represent.  They cant be corner points because the 
> display should be a circle, so what are they offsets from?  Any 
> clarity that someone can provide on how to use polar projection would 
> be very helpful. Thanks.
>
> PROJECTION     "proj=stere"
>        "lat_ts=75"
>        "north"
>        "lat_0=90"
>  END
>
We've been successful with

-9036842.762, -9036842.762, 9036842.762, 9036842.762