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. Thanks. Best wishes, John ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
