#include "slu_ddefs.h"
Functions | |
void | sp_preorder (superlu_options_t *options, SuperMatrix *A, int *perm_c, int *etree, SuperMatrix *AC) |
int | check_perm (char *what, int n, int *perm) |
int check_perm | ( | char * | what, | |
int | n, | |||
int * | perm | |||
) |
void sp_preorder | ( | superlu_options_t * | options, | |
SuperMatrix * | A, | |||
int * | perm_c, | |||
int * | etree, | |||
SuperMatrix * | AC | |||
) |
Purpose =======
sp_preorder() permutes the columns of the original matrix. It performs the following steps:
1. Apply column permutation perm_c[] to A's column pointers to form AC;
2. If options->Fact = DOFACT, then (1) Compute column elimination tree etree[] of AC'AC; (2) Post order etree[] to get a postordered elimination tree etree[], and a postorder permutation post[]; (3) Apply post[] permutation to columns of AC; (4) Overwrite perm_c[] with the product perm_c * post.
Arguments =========
options (input) superlu_options_t* Specifies whether or not the elimination tree will be re-used. If options->Fact == DOFACT, this means first time factor A, etree is computed, postered, and output. Otherwise, re-factor A, etree is input, unchanged on exit.
A (input) SuperMatrix* Matrix A in A*X=B, of dimension (A->nrow, A->ncol). The number of the linear equations is A->nrow. Currently, the type of A can be: Stype = NC or SLU_NCP; Mtype = SLU_GE. In the future, more general A may be handled.
perm_c (input/output) int* Column permutation vector of size A->ncol, which defines the permutation matrix Pc; perm_c[i] = j means column i of A is in position j in A*Pc. If options->Fact == DOFACT, perm_c is both input and output. On output, it is changed according to a postorder of etree. Otherwise, perm_c is input.
etree (input/output) int* Elimination tree of Pc'*A'*A*Pc, dimension A->ncol. If options->Fact == DOFACT, etree is an output argument, otherwise it is an input argument. Note: etree is a vector of parent pointers for a forest whose vertices are the integers 0 to A->ncol-1; etree[root]==A->ncol.
AC (output) SuperMatrix* The resulting matrix after applied the column permutation perm_c[] to matrix A. The type of AC can be: Stype = SLU_NCP; Dtype = A->Dtype; Mtype = SLU_GE.