When A is defined like this it is the linalg-Matrix. If you want to define a LinearAlgebra - Matrix, and so be able to use the Functions from the LinearAlgebra lib, you have to def it like this A = Matrix(...) with uppercase Letters I want to use Eigenvectors and Eigenvalue Functions from this package. I know its possible with linalg but i would prefere the other one thx

Forgot to say, that it works with the linalg lib but not with the LinearAlgebra lib. But I really woud prefere to use LinearAlgebra library. > restart; with(linalg); > A := matrix(3, 3, 3) [3 3 3] [3 3 3] [3 3 3] > sum(sum(A_(i,j),i=1..3),j=1..3) 27 > restart; with(LinearAlgebra); > A := matrix(3, 3, 3) [3 3 3] [3 3 3] [3 3 3] > sum(sum(A_(i,j),i=1..3),j=1..3) Error, bad index into Matrix thx