AN ALGORITHM FOR COMPUTING THE BLOCK TRIANGULAR FORM AND INVERSE OF A SPARSE MATRIX

We describe implementations of algorithms to compute the block triangular form of a square matrix(A) whose entries are with many zeros. Our object is to find a permutation matrix P such that PAP¡1 is completely reduced i.e., is partitioned in block triangular form so that all submatrices below its diagonal are 0 and all diagonal submatrices are square and irreducible. Then we use of these submatrices for computing inverse of the original matrix by some functions