csc_ilu csc_ilu0 csc_ilu_solve csc_ssor_solve csr_ilu csr_ilu0 csr_ilu_solve csr_ssor_solve csx_ds csx_ds_solve csx_ssor

csr_ilu0() void csr_ilu0 ( int  n, const double  val[], const int  rowptr[], const int  colind[], int  base, double  val2[], double  d[], int *  info  ) Incomplete LU decomposition without fill-in (ILU0) (CSR) Purpose This routine computes the incomplete LU decomposition, without fill-in, of the coefficient matrix A of the sparse linear equations. A = L * U + R where R is the difference from the complete LU decomposition. Assuming that R is small, the following preconditioner matrix is obtained by solving the equations using this decomposition. M = L * U This routine outputs the lower triangular matrix L and the upper triangular matrix U in val2[]. And the diagonal elements of U are copied to d[]. val2[] and d[] will be used by csr_ilu_solve(). Parameters [in] n Dimension of matrix A. (n >= 0) (If n = 0, returns without computation) [in] val[] Array val[lval] (lval >= nnz) (nnz is number of non-zero elements of matrix A) Values of non-zero elements of matrix A. [in] rowptr[] Array rowptr[lrowptr] (lrowptr >= n + 1) Row pointers of matrix A. [in] colind[] Array colind[lcolind] (lcolind >= nnz) Column indices of matrix A. [in] base Indexing of rowptr[] and colind[]. = 0: Zero-based (C style) indexing: Starting index is 0. = 1: One-based (Fortran style) indexing: Starting index is 1. [out] val2[] Array val2[lval2] (lval2 >= nnz) Values of non-zero elements of the lower triangular matrix L and the upper triangular matrix U. (nnz is same with the number of non-zero elements of A. The values are stored in the same location of lower and upper triangular elements of A.) [out] d[] Array d[ld] (ld >= n) The diagonal elements of upper triangular matrix U. [out] info = 0: Successful exit. = i < 0: The (-i)-th argument is invalid. = j > 0: Matrix is singular (j-th diagonal element is zero).