Thanks for explaining that, Kip. Yes, I've noted your changes in the narrative, particularly "1996 edition" and was puzzled by the whole paragraph. In a weary state I searched Voc for "c." which I'd never heard of and picked up "C." instead without realising it -- which made me even more puzzled. I began to think wildly about eigenvalues of permutation matrices. :-)
You're right to observe that we shouldn't go materially changing content. In APWJ Edn 1 however, where a para has become totally obsolete it has been omitted and a brief footnote inserted to record what has been omitted. I'll consider doing that here for APWJ Edn 2 and I'll reflect any changes back into the J Wiki. BTW where the book has footnotes I'm inserting the same text inline between square brackets. Ch 2 (Play103) illustrates. Ian Clark On Sun, May 24, 2009 at 10:39 PM, Kip Murray <[email protected]> wrote: > Perhaps your footnote could say, "The entry for c. Characteristic or > Eigenvalues was removed from the Dictionary some time after the 1998 > edition." > > No entry for c. is in the current Dictionary (see > http://www.jsoftware.com/help/ , click on Dic . Lower case c. used to be > between the pages for b. and upper case C.). > > More information follows, last paragraph important to me! > > I found c. Characteristic or Eigenvalues in Part III. Definitions of the > 1998 edition of the Dictionary with a note, "Not implemented in Release > 4.01". The definition (as transcribed by me from my printed copy of the > 1998 edition) said > > ----- > Characteristic or Eigenvalues c. 2 0 2 > > c. y yields the _characteristic_, _own_, or _eigen_ values of its argument, > arranged in ascending order on imaginary part within real within magnitude. > An atom or list y is treated as the table ,.y. > > 0 c. y is a diagonal matrix with the eigenvalues c. y on the diagonal. Also > _1 c. y and 1. y [thus it stands] are the left and right eigenvectors. If > i=: _1 0 1, then +/ . */ i c. y is y. > > Not implemented in Release 4.01. > ----- > > I added the phrase "1996 Edition" in the final APWJ Chapter 15 paragraph, > and you need to look for such unannounced changes in the articles I revised. > They are changes to bring the article up to date without materially > changing content. (Also note the 1996 Edition of the Dictionary is a better > reference than the 1998 edition, which has the typo indicated above. I do > not have the 1997 edition, and I do not know when the c. article was removed > from the Dictionary.) > > Kip Murray > > > Ian Clark wrote: >> >> APWJ Chapter 15 (Oh No Not Eigenvalues Again, as revised by Kip >> Murray) ends with the following paragraph... >> >> "The verb cm is a model of the monad of the c. primitive described in >> the J Introduction and Dictionary 1996 Edition. It differs in that the >> roots are given in order of descending magnitude, which is how the >> polynomial (p.) primitive provides them, rather than the ascending >> order prescribed in the Dictionary. Since c. has not yet been >> implemented, it's anyone's guess how p. and c. will be reconciled. >> I've brought this matter to the attention of the proper authorities, >> so they do at least know that the problem exists." >> >> Since c. is now listed in the J Dictionary, the reader may ask: how >> *has* it been reconciled with p.? >> >> I'd like to insert a footnote to this effect in Edn 2 of APWJ. >> >> Ian Clark >> Subeditor, APWJ 2nd edn. >> ---------------------------------------------------------------------- >> 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
