Approximating the Inverse of a Square Matrix with Application in Computation of the Moore-Penrose Inverse

Algorithm 3

n  =  10000;

A  =  SparseArray[{Band[{−700,  −200}]  ->  1.,  Band[{1,  1}]  ->  −1.5,

  Band[{1,  −400}]  ->  .9,  Band[{1,  −400}]  ->  −1.,

  Band[{2000,  200}]  ->  1.},  {n,  n},  0.]