I am having a problem in indexing a given matrix to be used in sigma. How can I make this work? x-y coordinate method > xy := Matrix(5, 2, {(1, 1) = 10, (1, 2) = 10, (2, 1) = -14, (2, 2) = -2, (3, 1) = -10, (3, 2) = -10, (4, 1) = 4, (4, 2) = -24, (5, 1) = 10, (5, 2) = 10}); > n := LinearAlgebra[RowDimension](xy); = print(`output redirected...`); # input placeholder 5 > > x := LinearAlgebra[Column](xy, 1); = print(`output redirected...`); # input placeholder Vector[column](%id = 194172504)