This must be a bug: a (+/ @: *)" 1 _ b 7 3 4 2 a (+/ @: (*"*))" 1 _ b 5 1 4 2
Henry Rich > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Roger Stokes > Sent: Saturday, June 14, 2008 3:44 AM > To: Programming forum > Subject: Re: [Jprogramming] LJ 22.4.4 Matrix Product > > > Patrick, > > Thanks for your message. > > I agree that your mp and mp2 give different results. > > In J504 they give the SAME result, the same as +/ . * as expected. > > I believe something must have changed btween j504 and J601. > > > What this change might be, I don't know. The release notes > for J601 show > that > f/@:g has been improved. > > Regards > > Roger Stokes. > > > ----- Original Message ----- > From: "Patrick van Beek" <[EMAIL PROTECTED]> > To: <[email protected]> > Sent: Saturday, June 14, 2008 4:27 AM > Subject: [Jprogramming] LJ 22.4.4 Matrix Product > > > > 22.4.4 of learning J has an equivalent definition of u @ (v > " (1+L, _)) > > being (u @: v) " (1+L, _) > > > > It then goes on to say > > > > +/.* means (+/ @: *)" 1 _ > > > > I get different answers for these two phrases: > > > > a=. >1 0 2; _1 3 1 > > b=. >3 1; 2 1;1 0 > > a +/ . * b > > 5 1 > > 4 2 > > mp =. (+/ @: *)" 1 _ > > mp2 =. +/ @ (* " 1 _) > > > > a mp b > > 7 3 > > 4 2 > > a mp2 b > > 5 1 > > 4 2 > > > > I came of with the following explicit definition though I > could not quite > > see why mp2 is equivalent since I had to change the rank of > the insert. > > > > +/"_1(a *"1 _ b) > > 5 1 > > 4 2 > > > > I could not derive the result of mp explicitly. Could > someone explain how > > the result for a mp b is derived and so help me understand > what mp is > > doing > > different to mp2? > > > > Thanks, > > > > Patrick > > > > > > > > > ---------------------------------------------------------------------- > > 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
