[Jprogramming] sparse matrices

[Don & Cathy Kelly]

The J dictionary deals with conversion between the full and sparse 
matrix forms

] M=:> 5 _1;_1 6
5 _1
_1 6

$.M
0 0 │ 5
0 1 │ _1
1 0 │ _1
1 1 │ 6

is fine but I would like to enter the row,column and value list as it 
appears in $.M (i.e. as an m by 3 array
It would also be nice to not have to repeat items in the list (i.e 
M(0,1)=M(1,0)

Don

----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm