  The approximation of tensors is important for the efficient numerical
treatment of high dimensional problems, but it remains an extremely challenging
task. One of the most popular approach to tensor approximation is the
alternating least squares method. In our study, the convergence of the
alternating least squares algorithm is considered. The analysis is done for
arbitrary tensor format representations and based on the multiliearity of the
tensor format. In tensor format representation techniques, tensors are
approximated by multilinear combinations of objects lower dimensionality. The
resulting reduction of dimensionality not only reduces the amount of required
storage but also the computational effort.
