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
