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/*! @file ddiagonal.c
* \brief Auxiliary routines to work with diagonal elements
*
* <pre>
* -- SuperLU routine (version 4.0) --
* Lawrence Berkeley National Laboratory
* June 30, 2009
* </pre>
*/
#include "slu_ddefs.h"
int dfill_diag(int n, NCformat *Astore)
/* fill explicit zeros on the diagonal entries, so that the matrix is not
structurally singular. */
{
double *nzval = (double *)Astore->nzval;
int *rowind = Astore->rowind;
int *colptr = Astore->colptr;
int nnz = colptr[n];
int fill = 0;
double *nzval_new;
double zero = 0.0;
int *rowind_new;
int i, j, diag;
for (i = 0; i < n; i++)
{
diag = -1;
for (j = colptr[i]; j < colptr[i + 1]; j++)
if (rowind[j] == i) diag = j;
if (diag < 0) fill++;
}
if (fill)
{
nzval_new = doubleMalloc(nnz + fill);
rowind_new = intMalloc(nnz + fill);
fill = 0;
for (i = 0; i < n; i++)
{
diag = -1;
for (j = colptr[i] - fill; j < colptr[i + 1]; j++)
{
if ((rowind_new[j + fill] = rowind[j]) == i) diag = j;
nzval_new[j + fill] = nzval[j];
}
if (diag < 0)
{
rowind_new[colptr[i + 1] + fill] = i;
nzval_new[colptr[i + 1] + fill] = zero;
fill++;
}
colptr[i + 1] += fill;
}
Astore->nzval = nzval_new;
Astore->rowind = rowind_new;
SUPERLU_FREE(nzval);
SUPERLU_FREE(rowind);
}
Astore->nnz += fill;
return fill;
}
int ddominate(int n, NCformat *Astore)
/* make the matrix diagonally dominant */
{
double *nzval = (double *)Astore->nzval;
int *rowind = Astore->rowind;
int *colptr = Astore->colptr;
int nnz = colptr[n];
int fill = 0;
double *nzval_new;
int *rowind_new;
int i, j, diag;
double s;
for (i = 0; i < n; i++)
{
diag = -1;
for (j = colptr[i]; j < colptr[i + 1]; j++)
if (rowind[j] == i) diag = j;
if (diag < 0) fill++;
}
if (fill)
{
nzval_new = doubleMalloc(nnz + fill);
rowind_new = intMalloc(nnz+ fill);
fill = 0;
for (i = 0; i < n; i++)
{
s = 1e-6;
diag = -1;
for (j = colptr[i] - fill; j < colptr[i + 1]; j++)
{
if ((rowind_new[j + fill] = rowind[j]) == i) diag = j;
s += fabs(nzval_new[j + fill] = nzval[j]);
}
if (diag >= 0) {
nzval_new[diag+fill] = s * 3.0;
} else {
rowind_new[colptr[i + 1] + fill] = i;
nzval_new[colptr[i + 1] + fill] = s * 3.0;
fill++;
}
colptr[i + 1] += fill;
}
Astore->nzval = nzval_new;
Astore->rowind = rowind_new;
SUPERLU_FREE(nzval);
SUPERLU_FREE(rowind);
}
else
{
for (i = 0; i < n; i++)
{
s = 1e-6;
diag = -1;
for (j = colptr[i]; j < colptr[i + 1]; j++)
{
if (rowind[j] == i) diag = j;
s += fabs(nzval[j]);
}
nzval[diag] = s * 3.0;
}
}
Astore->nnz += fill;
return fill;
}
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