Creates an object of a tensor train class. Syntax:
coeff - coefficient in front of the spin operator, usually be the interaction magnitude
kronterms - column cell array of matrices whose Krone- cker product makes up the spin operator.
tolerance - maximum deviation in the 2-norm between the TT representation and the flat matrix repre- sentation that the TT formalism is allowed to introduce.
If multiple columns are supplied in kronterms, multiple coefficients are given in coeff, and multiple tolerances are given in tolerance, the resulting tensor train is assumed to be the sum of the individu- al tensor trains specified in different columns.