Then, and function that requires PI
of half_PI can check first to see if it is cached  as __gpi__  and if so pull it back, or if not calculate
it.   If the context does not change than I half some whopping value of PI for the duration of the 
context (but, and this is the big but, if I don't need it --- then it never gets bound).


um, sorry, I wixed my mords...   please forgive,  

 "Then, and only then, a function that requires PI or half_PI  
will first check to see if  __gpi__  has been cached and if so pull it back, or if not calculate it (once).  If the context
does not change then the function can take half of some whopping value of PI, for the duration of the context, and
use that,  but if not needed for the context will never bind it !


marcus