void Transpose (const Table &A, Table &At, int _ncols_A)
{
const int *i_A = A.GetI();
const int *j_A = A.GetJ();
const int nrows_A = A.Size();
const int ncols_A = (_ncols_A < 0) ? A.Width() : _ncols_A;
const int nnz_A = i_A[nrows_A];
At.SetDims (ncols_A, nnz_A);
int *i_At = At.GetI();
int *j_At = At.GetJ();
for (int i = 0; i <= ncols_A; i++)
i_At[i] = 0;
for (int i = 0; i < nnz_A; i++)
i_At[j_A[i]+1]++;
for (int i = 1; i < ncols_A; i++)
i_At[i+1] += i_At[i];
for (int i = 0; i < nrows_A; i++)
for (int j = i_A[i]; j < i_A[i+1]; j++)
j_At[i_At[j_A[j]]++] = i;
for (int i = ncols_A; i > 0; i--)
i_At[i] = i_At[i-1];
i_At[0] = 0;
}
void Mult (const Table &A, const Table &B, Table &C)
{
int i, j, k, l, m;
const int *i_A = A.GetI();
const int *j_A = A.GetJ();
const int *i_B = B.GetI();
const int *j_B = B.GetJ();
const int nrows_A = A.Size();
const int nrows_B = B.Size();
const int ncols_A = A.Width();
const int ncols_B = B.Width();
MFEM_VERIFY( ncols_A <= nrows_B, "Table size mismatch: ncols_A = " << ncols_A
<< ", nrows_B = " << nrows_B);
Array<int> B_marker (ncols_B);
for (i = 0; i < ncols_B; i++)
B_marker[i] = -1;
int counter = 0;
for (i = 0; i < nrows_A; i++)
{
for (j = i_A[i]; j < i_A[i+1]; j++)
{
k = j_A[j];
for (l = i_B[k]; l < i_B[k+1]; l++)
{
m = j_B[l];
if (B_marker[m] != i)
{
B_marker[m] = i;
counter++;
}
}
}
}
C.SetDims (nrows_A, counter);
for (i = 0; i < ncols_B; i++)
B_marker[i] = -1;
int *i_C = C.GetI();
int *j_C = C.GetJ();
counter = 0;
for (i = 0; i < nrows_A; i++)
{
i_C[i] = counter;
for (j = i_A[i]; j < i_A[i+1]; j++)
{
k = j_A[j];
for (l = i_B[k]; l < i_B[k+1]; l++)
{
m = j_B[l];
if (B_marker[m] != i)
{
B_marker[m] = i;
j_C[counter] = m;
counter++;
}
}
}
}
}