About the inversion of some matrices arising in the dynamics of crystal lattices with defects
Otto Litzman, Miroslav Bartušek · Journal of Physics C Solid State Physics · 1971
The authors find inverse (D 0 -ZI+S) -1 where the matrix S has only a small number of elements different from zero. It is shown that the usual formulae for the inversion can be simplified if the matrix S is singular.