I have a 3D tensor T of size (nrows, ncols, ncols), which I would like to multiply with a vector x of size nrows.
However, T will be a huge sparse tensor with 6×6 nonzero entries in each row;
thus, it would be useful to store T in a sparse format.
The most convenient way would be to define a Tsparse tensor of size (nrows, 6, 6) and a “pointer” matrix p of size (nrows, 6) which stores the indices of the nonzero entries for each row.