That is the way to do it. The approach is this: that expression is the most "natural" way in J to do the task. If the current performance proves to be inadequate then we can try to improve the implementation, rather than invent some alternative (such as another primitive or m!:n).
----- Original Message ----- From: "John Randall" <[EMAIL PROTECTED]> To: "Programming forum" <[email protected]> Sent: Thursday, April 06, 2006 3:08 PM Subject: Re: [Jprogramming] Padding a matrix Thanks to all for your comments on this. Here's a related problem. Suppose I have a sparse matrix m. I can get the index array i and value list x using i=:4 $. m x=:5 $. m How do you do the reverse, that is, amend an initially empty sparse matrix m with these indices and values? I am currently using x (<"1 i) } m but I fear this reflects my ignorance. ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
