On Fri, 1 Dec 2006, Roger Hui wrote:
> In SATN-42 (Sharp APL Technical Notes), 1982-04-01,
> Ken Iverson described several uses monads derived
> from the dot operator. Translated from APL into
> J, these are:
>
> +./ . *.
> + / . *.
> <./ . +
> >./ . +
> <./ . *
> >./ . *
> <./ . >.
> >./ . <.
Many thanks for the reference. Have you any pointers as to
how the above are used/can be useful? - I'm having a tough time
understanding them! Needless (& sad) to say I couldn't find
SATN-42 available anywhere.
> Computation of f/ .g can be sped up for f and g
> in domains which permit Gaussian elimination.
> This has not been done in the current
> implementation.
I hope that general Gaussian elimination isn't too high up your list
of priorities! Fortunately here the end-user, i.e. myself, can take
advantage of J's existing Gaussian elimination because
((~:/ . *.) -: (2 | +/ . *)) A NB. A is square 0-1 matrix
1
However, this won't work for a general finite field GF(q), where
multiplication is not the same as q&|@*
- Regards, Ewart
J.E.H.Shaw [Ewart Shaw] [EMAIL PROTECTED] TEL: +44 2476 523069
Department of Statistics, University of Warwick, Coventry CV4 7AL, UK
http://www.warwick.ac.uk/statsdept http://www.ewartshaw.co.uk
Will read usenet posts up to the first insult (which may be in the Subject)
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
