A New High-Order Stable Numerical Method for Matrix Inversion

Algorithm 3

m  = 1500; k = 1800; number = 30; SeedRandom[1234];

Table[A[l]  = SparseArray[{Band[{400, 10}, {m, k}]  -> Random[]  - I,

  Band[{10, 200}, {m, k}]  -> {1.1, -Random[]},

  Band[{-60, 100}]  -> -3.02, Band[{-100, 500}]  -> 3.1 I}, {m, k}, 0.];, {l, number}];

Id = SparseArray[{{i_,  i_}  -> 1.}, {m, m}, 0.];