http://en.wikipedia.org/wiki/The_Magical_Number_Seven,_Plus_or_Minus_Two
7 was the threshold I picked for using APVs in the linear representation of a numeric vector. Other space-saving tricks are also used. lr=: 3 : '5!:5 <''y''' lr 3 + 4 * i. _123456 493823+_4*i.123456 lr 123456 $ 40 123456$40 lr 123456 $ 'a' 123456$'a' ----- Original Message ----- From: Ian Shannon <[email protected]> Date: Thursday, February 11, 2010 14:35 Subject: Re: [Jgeneral] Bond to vector of infinity To: General forum <[email protected]> > Roger, > > Any insight as to why 7 is a magic number? > > BTW. neat piece of replacement to produce _*i.8. > Though it does depend on 0 = x * 0 , rather than _ = _ * x > (x scalar). Is this type of replacement > general where the interpreter needs to keep a vector? > > Ian > > > -----Original Message----- > From: [email protected] [mailto:general- > [email protected]] On Behalf Of Roger Hui > Sent: Friday, February 12, 2010 3:17 AM > To: General forum > Subject: Re: [Jgeneral] Bond to vector of infinity > > Fixed for the next release. Thank you for finding and > reporting this error. > > > > ----- Original Message ----- > From: Ian Shannon <[email protected]> > Date: Wednesday, February 10, 2010 22:35 > Subject: [Jgeneral] Bond to vector of infinity > To: "[email protected]" <[email protected]> > > > > > Hi there, > > > > Notification of a interpreter error. The error is something like: > > If a vector to be bonded (on either left or right) includes > infinity > > (+ and/or -) and is longer than 7 items then interpreter > returns NaN > > error. > > > > However if vector is longer than 7 items the interpreter > > (cleverly) can sometimes optimise. > > Eg 0 _ _ _ _ _ _ _ _ _ becomes > > (_*i.10) and error does not occur. > > > > > > > > J602 on win XP SP2. > > > > > > ========= > > NB. Display of interpreter error > > 9!:12 '' > > 6 > > 9!:14 '' > > j602/2008-03-03/16:45 > > ,&_ _ _ _ _ _ > > ┌─┬─┬───────────┐ > > │,│&│_ _ _ _ _ _│ > > └─┴─┴───────────┘ > > ,& _ _ _ _ _ _ _ > > ┌─┬─┬─────────────┐ > > │,│&│_ _ _ _ _ _ _│ > > └─┴─┴─────────────┘ > > ,& _ _ _ _ _ _ _ _ > > |NaN error > > ,& __ __ __ __ __ __ __ > > ┌─┬─┬────────────────────┐ > > │,│&│__ __ __ __ __ __ __│ > > └─┴─┴────────────────────┘ > > ,& __ __ __ __ __ __ __ __ > > |NaN error > > ,& 0 __ __ __ __ __ __ __ __ > > ┌─┬─┬─────────────────────────┐ > > │,│&│0 __ __ __ __ __ __ __ __│ > > └─┴─┴─────────────────────────┘ > > ,& 0 __ __ __ __ __ __ __ __ 0 > > ┌─┬─┬───────────────────────────┐ > > │,│&│0 __ __ __ __ __ __ __ __ 0│ > > └─┴─┴───────────────────────────┘ > > ,& __ __ __ __ 0 0 0 0 > > |NaN error > > ,& __ __ __ 0 0 0 0 > > ┌─┬─┬────────────────┐ > > │,│&│__ __ __ 0 0 0 0│ > > └─┴─┴────────────────┘ > > > > > > 7 appears to be the magic number for the length of the > constant > > vector to bond. > > > > The error also occurs when bonding with other functions (on > both > > left and right). > > > > > > Note I cannot use the wiki > > http://www.jsoftware.com/jwiki/System/Interpreter/Bugs > > > > as it won't let me reset the password - it says that recovery > > token (copied out of return email) is invalid. Please let > > me know how to get into the system. > > > > > > Ian ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
