diff2use
a family of lattice vectors defining the data covariations to be used for the MSE estimation. A matrix with as many columns as lattice vectors. Each column contains the vector coordinates in the basis defined by the lattice generating matrix. Optional: a default value is computed. If isotropy is assumed, the lattice generating matrix (3 main basis vectors). Otherwise, 3 face diagonal lattice vectors are added to the 3 main basis vectors.