Many of the inverse were motivated by f&.g . See http://www.jsoftware.com/jwiki/Essays/Under .
When I first learned APL decades ago I found it amusing to find novel inner products (e.g. not-equal dot equal, used in finding leap years). Now I am amused by finding neat duals. My favorite: If x ack y is f&.(3&+) y, then (x+1) ack y is f^:(1+y)&.(3&+) 1, where ack is the Ackermann function. On Fri, May 31, 2013 at 7:00 PM, elton wang <[email protected]> wrote: > I guess this may deserve a new thread: > for the inverse of m&|: like > 3&|: b._1 > (] |:~ 3 C.^:_1 i.@#@$) :.(3&|:) > > How does J find this inverse? is this explicitly coded in J or J > automatically figures this out by some rules? Either way, this is amazing. ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
