"A really simple approach would be " for integer powers,
pow =: [: */ #~ ----- Original Message ----- From: Raul Miller <[email protected]> To: Programming forum <[email protected]> Cc: Sent: Tuesday, August 5, 2014 2:36:53 AM Subject: Re: [Jprogramming] Power for the powerless A really simple approach would be to use T. pow=: ^ T. 99 That gives you a polynomial expression Here's a shorter version: ^ T. 4 1 1 0.5 0.16666666666666666&p. Here's the more accurate version: (^ -: pow) 10 11 12 1 It's not necessarily efficient, but it's really simple. Thanks, -- Raul On Tue, Aug 5, 2014 at 1:01 AM, Dan Bron <[email protected]> wrote: > That's a long page, but in brief: can you calculate the power series > without using ^ explicitly or implicitly (e.g. via t. or #: etc)? Are all > the ^s I see in those power series easily replaced by instances of > */@:#"0 ? > > In other words, does that page teach me how to do the trick when literally > the only mathematical functions in my toolbox are (dyads) + - * % and > (monad) | ? > > -Dan > > ----- Original Message --------------- > > Subject: Re: [Jprogramming] Power for the powerless > From: Roger Hui <[email protected]> > Date: Mon, 4 Aug 2014 21:51:08 -0700 > To: Programming forum <[email protected]> > > ?Can you not just use power series (for both exp and ln)? See > http://www.jsoftware.com/jwiki/Essays/Extended%20Precision%20Functions .? > > > On Mon, Aug 4, 2014 at 9:39 PM, Dan Bron <[email protected]> wrote: > > > There's a StackExchange puzzle which challeges us to implement power > (i.e. > > dyad ^) using only the simple arithmetic dyads + - * % and monad | [1]. > In > > other words, we may not use ^ or ^. or variants. There are still several > > open questions on the puzzle, not least of which involves the domain of > > the inputs (can the base be negative?) and range of the outputs (how much > > precision is required?), but neverthless we can make some assumptions and > > start to sketch an approach. > > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
