I sent a msg yesterday and I don't see it in the forum nor has it come back to me. Anybody seen it (for this topic)? /Dan
--- On Fri, 1/9/09, Devon McCormick <[email protected]> wrote: > From: Devon McCormick <[email protected]> > Subject: Re: [Jprogramming] Matrix spread > To: "Programming forum" <[email protected]> > Date: Friday, January 9, 2009, 5:36 PM > This is not as direct as the solutions using expansion with > a complex > expander but it's one of those things I thought of and > it worked the first > time just as I'd conceived it: concatenation under > rotation: > > 0,&.(4&|."1)0,&.(4&|.)>:i.5 5 > 1 2 3 4 0 5 > 6 7 8 9 0 10 > 11 12 13 14 0 15 > 16 17 18 19 0 20 > 0 0 0 0 0 0 > 21 22 23 24 0 25 > > The only advantage it might have would be for inserting > non-zero rows or > columns. > > The symmetry of inserting both the same row and column > makes me wonder if > there's a more general, adverbial method to do both at > once. > Experimentation showed me this: > > (0&,&.(4&|.)) (1 : 'u u"1 > y')mat > 1 2 3 4 0 5 > 6 7 8 9 0 10 > 11 12 13 14 0 15 > 16 17 18 19 0 20 > 0 0 0 0 0 0 > 21 22 23 24 0 25 > > Which extends interestingly (though maybe not usefully): > > (0 99&,&.(4&|.)) (1 : 'u u"1 > y')mat > 1 2 3 4 0 99 5 > 6 7 8 9 0 99 10 > 11 12 13 14 0 99 15 > 16 17 18 19 0 99 20 > 0 99 0 0 0 0 0 > 21 22 23 24 0 99 25 > > On Fri, Jan 9, 2009 at 4:47 PM, Raul Miller > <[email protected]> wrote: > > > On Fri, Jan 9, 2009 at 4:40 PM, Brian Schott > <[email protected]> > > wrote: > > > I think this is more complete. > > > > > > 1 1 1 1j1 1 #"1]1 1 1 1j1 1 #>:i. 5 5 > > > 1 2 3 4 0 5 > > > 6 7 8 9 0 10 > > > 11 12 13 14 0 15 > > > 16 17 18 19 0 20 > > > 0 0 0 0 0 0 > > > 21 22 23 24 0 25 > > > > Yes, thank you, I did not read carefully enough. > > > > Or: > > m=:1+i.5 5 > > b=:1 1 1 1 0 1 > > b #inv b#inv"1 m > > 1 2 3 4 0 5 > > 6 7 8 9 0 10 > > 11 12 13 14 0 15 > > 16 17 18 19 0 20 > > 0 0 0 0 0 0 > > 21 22 23 24 0 25 > > > > -- > > Raul > > > ---------------------------------------------------------------------- > > For information about J forums see > http://www.jsoftware.com/forums.htm > > > > > > -- > Devon McCormick, CFA > ^me^ at acm. > org is my > preferred e-mail > ---------------------------------------------------------------------- > For information about J forums see > http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
