For fun I copied this to the scratch area and executing it from there using esc r the results are only shown in the log if you use smoutput. changed it to
x=:1+i.5 x 1 2 3 4 5 x=: 44 (2}) x 1 2 44 4 5 smoutput x now in the log it shows 1 2 44 4 5 so you can change the vector and save it again using the same name. You can do measurements and see how fast it is. So the simple answer to your question is "Am I missing something here?" yes. 2012/1/6 Blake McBride <bl...@mcbride.name> > Greetings, > > Going through J I found that: > > x=:1+i.5 > x > 1 2 3 4 5 > 44 (2}) x > 1 2 44 4 5 > x > 1 2 3 4 5 > > It seems that J doesn't actually make an indexed assignment. It seems > more like it creates a copy of the array with the specified > modifications. This is actually quite shocking. Index assignment to > a very large array in most languages is a very fast and simple > operation. It is also very memory efficient. Creating a modified > copy of a very large array has a much, much greater time and space > cost. Further, multiplying this (unnecessary) cost over a great > number of operations can drastically (and unnecessarily) affect > performance negatively. > > Am I missing something here? > > Thanks. > > Blake McBride > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > -- Björn Helgason, Verkfræðingur Fornustekkum II 781 Hornafirði, t-póst: gos...@gmail.com gsm: +3546985532 twitter: @flugfiskur http://groups.google.com/group/J-Programming Tæknikunnátta höndlar hið flókna, sköpunargáfa er meistari einfaldleikans góður kennari getur stigið á tær án þess að glansinn fari af skónum /|_ .-----------------------------------. ,' .\ / | Með léttri lund verður | ,--' _,' | Dagurinn í dag | / / | Enn betri en gærdagurinn | ( -. | `-----------------------------------' | ) | (\_ _/) (`-. '--.) (='.'=) ♖♘♗♕♔♙ `. )----' (")_(") ☃☠ ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
