/**
* An other implementation of solve() that processes the matrices in a different order.
* It seems to have the same runtime performance as {@link #solve} and is more complicated.
* It is being kept around to avoid future replication of work.
*
* @param b A matrix that is n by m. Not modified.
* @param x An n by m matrix where the solution is writen to. Modified.
*/
//@Override
public override void solve(DMatrixRMaj b, DMatrixRMaj x)
{
if (b.numCols != x.numCols || b.numRows != numRows || x.numRows != numCols)
{
throw new ArgumentException("Unexpected matrix size");
}
if (b != x)
{
SpecializedOps_DDRM.copyChangeRow(pivot, b, x);
}
else
{
throw new ArgumentException("Current doesn't support using the same matrix instance");
}
// Copy right hand side with pivoting
int nx = b.numCols;
double[] dataX = x.data;
// Solve L*Y = B(piv,:)
for (int k = 0; k < numCols; k++)
{
for (int i = k + 1; i < numCols; i++)
{
for (int j = 0; j < nx; j++)
{
dataX[i * nx + j] -= dataX[k * nx + j] * dataLU[i * numCols + k];
}
}
}
// Solve U*X = Y;
for (int k = numCols - 1; k >= 0; k--)
{
for (int j = 0; j < nx; j++)
{
dataX[k * nx + j] /= dataLU[k * numCols + k];
}
for (int i = 0; i < k; i++)
{
for (int j = 0; j < nx; j++)
{
dataX[i * nx + j] -= dataX[k * nx + j] * dataLU[i * numCols + k];
}
}
}
}
