I asked a question about symbolic matrices and LU decompositions in https://ask.sagemath.org/question/62878/how-to-define-a-matrix-with-variables-in-sagemath/
I have another question about LU decomposition. I would like to define a matrix xi(t) as a matrix with 1's on the diagonal and with t at (i,i+1) position, and all other entries are 0. Let g=xi1(t1)⋯xim(tm)T, where T is a diagonal matrix with entries λ1,…,λn. I would like to define this matrix in Sage and apply LU decomposition to it. Now t1,…,tm,λ1,…,λn are symbols. How to do this in Sage? Thank you very much.