Upper or right tri-mat: utmfv=: 3 : 0 bv=. ;<\.1,~0$~2-~-:>:%:>:4*+:#y |."1 bv |.;. 2 y )
Lower or left tri-mat; ltmfv=: 3 : 0 bv=. ;<\1,0$~2-~-:>:%:>:4*+:#y bv ,;. 1 y ) utmfv 1+i.6 1 2 3 0 4 5 0 0 6 ltmfv 1+i.6 1 0 0 2 3 0 4 5 6 It's a pity that 'utmfv' suffers from the double reversing. =@@i ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
