neville holmes <[EMAIL PROTECTED]> wrote: > I have dropped working in J pending the restoring > of [: and ]: as functions like [. and ]., and unlike the > dropped lev and dex conjunctions, to allow me to > avoid explicit coding, so I have just been skimming > this forum's discussions. (Not that I really expect > this change to take place, but hope springs eternal.)
Could you please elaborate on what you mean by this? Just which functions of [: and ]: would you want "restored", and in which J version did they exist? There are already two verbs that are analagous to [. and ]. They are [ and ] As for [: , it already has a different and incompatible meaning that is very firmly entrenched in the language, so it's something I would not expect to ever change. > For floating point computation, in particular for the > common multiply and accumulate kind, truncation > error can be avoided by doing the arithmetic and > accumulation in a long fixed point register. This > was implemented in the '70s in microcode on an > IBM mainframe (google acrith for details) and later > on a chip (see www.bookpool.com/sm/3211838708). > Multicore processors could well provide support > for such arithmetic. Indeed, I understand that the > revised IEEE standard for binary floating point > arithmetic could include such arithmetic under > the name "complete arithmetic". For integers, it's easy - a double-word will always suffice. For reals, it's harder - I think you would need around 2048 bits for double precision (which J uses), and 32K bits for long doubles. -- Mark D. Niemiec <[EMAIL PROTECTED]> ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
