/**
* Extract the diagonal entries from *triangular* Csparse matrix __or__ a
* cholmod_sparse factor (LDL = TRUE).
*
* @param pslot 'p' (column pointer) slot of Csparse matrix/factor
* @param xslot 'x' (non-zero entries) slot of Csparse matrix/factor
* @param perm_slot 'perm' (= permutation vector) slot of corresponding CHMfactor;
* only used for "diagBack"
* @param resultKind a (SEXP) string indicating which kind of result is desired.
*
* @return a SEXP, either a (double) number or a length n-vector of diagonal entries
*/
SEXP diag_tC(SEXP pslot, SEXP xslot, SEXP perm_slot, SEXP resultKind)
{
int n = length(pslot) - 1, /* n = ncol(.) = nrow(.) */
*x_p = INTEGER(pslot),
*perm = INTEGER(perm_slot);
double *x_x = REAL(xslot);
/* ^^^^^^ ^^^^ FIXME[Generalize] to INTEGER(.) / LOGICAL(.) / ... xslot !*/
return diag_tC_ptr(n, x_p, x_x, perm, resultKind);
}
/**
* Fast version of getting at the diagonal matrix D of the
* (generalized) simplicial Cholesky LDL' decomposition of a
* (sparse symmetric) dsCMatrix.
*
* @param Ap symmetric CsparseMatrix
* @param permP logical indicating if permutation is allowed
* @param resultKind an (SEXP) string indicating which kind of result
* is desired.
*
* @return SEXP containing either the vector diagonal entries of D,
* or just sum_i D[i], prod_i D[i] or sum_i log(D[i]).
*/
SEXP dsCMatrix_LDL_D(SEXP Ap, SEXP permP, SEXP resultKind)
{
CHM_FR L;
SEXP ans;
int c_pr = c.print;
c.print = 0;/* stop CHOLMOD printing; we cannot suppress it (in R), and
have error handler already */
L = internal_chm_factor(Ap, asLogical(permP),
/*LDL*/ 1, /*super*/0, /*Imult*/0.);
c.print = c_pr;
ans = PROTECT(diag_tC_ptr(L->n,
L->p,
L->x,
L->Perm,
resultKind));
cholmod_l_free_factor(&L, &c);
UNPROTECT(1);
return(ans);
}
