Thanks, Raul. You are always so prompt with your help! I am yet to decipher your solution, but your suggestion regarding 2 column table is bang on point.
My own approach was something like this: find nub of the 2nd column, then for each element in the nub collect all occurences of it, and sum over the coeffns. On Mon, 25 Nov 2019, 21:56 Raul Miller, <[email protected]> wrote: > Yes, definitely. > > For example, consider: > > <"1 ({:"1 (+&.>/@:({."1), (<0 1){])/. ])>v1 > > Or, > > f=: 13 :'<"1 ({:"1 (+&.>/@:({."1), (<0 1){])/. ])>y' > f v1 > > That said, this example may fall apart for your general case? (I don't > know what that is...) > > Specifically, I don't know why the top level structure of v1 and v2 > would be a list of boxed entities if they are always pairs. It seems > to me that a table of two columns would be a more natural expression > of that, if that's the case. > > Thanks, > > -- > Raul > > > On Mon, Nov 25, 2019 at 11:12 AM Arnab Chakraborty <[email protected]> > wrote: > > > > Dear all, > > > > I am trying to implement a geometric algebra system in J. I have done > > much of the stuff, but is getting stuck at one point. Hence this email. > > > > Basically, I have a list of boxes like > > > > v1=: (<2.3; 2 3 4), (<3.9; 1 2), <3.1; 2 3 4 > > > > This represents a (multi)vector whose math representation is > > > > 2.3 * e_{234} + 3.9 * e_{12} + 3.1 * e_{234}. > > > > Here the e_{...}'s are some basis vectors. As you can see, e_{234} occurs > > twice in the list, and so this vector may be reduced to > > > > 5.4 * e_{234} + 3.9 * e_{12}. > > > > In J this should be > > > > v2=:(<5.4; 2 3 4), <3.9; 1 2 > > > > I want to write a monad f such that f v1 is v2. > > > > Any idea? > > > > Thanks and regards. > > > > Arnab. > > ---------------------------------------------------------------------- > > 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
