// Use Gaussian Elimination to solve the matrices
protected static bool GaussElim(uint rows, uint leftcols, ushort[] leftmatrix, ushort[] rightmatrix, uint datamissing)
{
//if (noiselevel == CommandLine::nlDebug)
//{
// for (unsigned int row=0; row<rows; row++)
// {
// cout << ((row==0) ? "/" : (row==rows-1) ? "\\" : "|");
// for (unsigned int col=0; col<leftcols; col++)
// {
// cout << " "
// << hex << setw(G::Bits>8?4:2) << setfill('0')
// << (unsigned int)leftmatrix[row*leftcols+col];
// }
// cout << ((row==0) ? " \\ /" : (row==rows-1) ? " / \\" : " | |");
// for (unsigned int col=0; col<rows; col++)
// {
// cout << " "
// << hex << setw(G::Bits>8?4:2) << setfill('0')
// << (unsigned int)rightmatrix[row*rows+col];
// }
// cout << ((row==0) ? " \\" : (row==rows-1) ? " /" : " | |");
// cout << endl;
// cout << dec << setw(0) << setfill(' ');
// }
//}
// Because the matrices being operated on are Vandermonde matrices
// they are guaranteed not to be singular.
// Additionally, because Galois arithmetic is being used, all calulations
// involve exact values with no loss of precision. It is therefore
// not necessary to carry out any row or column swapping.
// Solve one row at a time
//int progress = 0;
// For each row in the matrix
for (uint row = 0; row < datamissing; row++)
{
// NB Row and column swapping to find a non zero pivot value or to find the largest value
// is not necessary due to the nature of the arithmetic and construction of the RS matrix.
// Get the pivot value.
ushort pivotvalue = rightmatrix[row * rows + row];
if (pivotvalue == 0)
{
//cerr << "RS computation error." << endl;
return(false);
}
// If the pivot value is not 1, then the whole row has to be scaled
if (pivotvalue != 1)
{
for (uint col = 0; col < leftcols; col++)
{
if (leftmatrix[row * leftcols + col] != 0)
{
leftmatrix[row * leftcols + col] = processor.Divide(leftmatrix[row * leftcols + col], pivotvalue);
}
}
rightmatrix[row * rows + row] = 1;
for (uint col = row + 1; col < rows; col++)
{
if (rightmatrix[row * rows + col] != 0)
{
rightmatrix[row * rows + col] = processor.Divide(rightmatrix[row * rows + col], pivotvalue);
}
}
}
// For every other row in the matrix
for (uint row2 = 0; row2 < rows; row2++)
{
// Define MPDL to skip reporting and speed things up
//#ifndef MPDL
// if (noiselevel > CommandLine::nlQuiet)
// {
// int newprogress = (row*rows+row2) * 1000 / (datamissing*rows);
// if (progress != newprogress)
// {
// progress = newprogress;
// cout << "Solving: " << progress/10 << '.' << progress%10 << "%\r" << flush;
// }
// }
//#endif
if (row != row2)
{
// Get the scaling factor for this row.
ushort scalevalue = rightmatrix[row2 * rows + row];
if (scalevalue == 1)
{
// If the scaling factor happens to be 1, just subtract rows
for (uint col = 0; col < leftcols; col++)
{
if (leftmatrix[row * leftcols + col] != 0)
{
leftmatrix[row2 * leftcols + col] = processor.Minus(leftmatrix[row2 * leftcols + col], leftmatrix[row * leftcols + col]);
}
}
for (uint col = row; col < rows; col++)
{
if (rightmatrix[row * rows + col] != 0)
{
rightmatrix[row2 * rows + col] = processor.Minus(rightmatrix[row2 * rows + col], rightmatrix[row * rows + col]);
}
}
}
else if (scalevalue != 0)
{
// If the scaling factor is not 0, then compute accordingly.
for (uint col = 0; col < leftcols; col++)
{
if (leftmatrix[row * leftcols + col] != 0)
{
leftmatrix[row2 * leftcols + col] = processor.Multiply(processor.Minus(leftmatrix[row2 * leftcols + col], leftmatrix[row * leftcols + col]), scalevalue);
}
}
for (uint col = row; col < rows; col++)
{
if (rightmatrix[row * rows + col] != 0)
{
rightmatrix[row2 * rows + col] = processor.Multiply(processor.Minus(rightmatrix[row2 * rows + col], rightmatrix[row * rows + col]), scalevalue);
}
}
}
}
}
}
//if (noiselevel > CommandLine::nlQuiet)
// cout << "Solving: done." << endl;
//if (noiselevel == CommandLine::nlDebug)
//{
// for (unsigned int row=0; row<rows; row++)
// {
// cout << ((row==0) ? "/" : (row==rows-1) ? "\\" : "|");
// for (unsigned int col=0; col<leftcols; col++)
// {
// cout << " "
// << hex << setw(G::Bits>8?4:2) << setfill('0')
// << (unsigned int)leftmatrix[row*leftcols+col];
// }
// cout << ((row==0) ? " \\ /" : (row==rows-1) ? " / \\" : " | |");
// for (unsigned int col=0; col<rows; col++)
// {
// cout << " "
// << hex << setw(G::Bits>8?4:2) << setfill('0')
// << (unsigned int)rightmatrix[row*rows+col];
// }
// cout << ((row==0) ? " \\" : (row==rows-1) ? " /" : " | |");
// cout << endl;
// cout << dec << setw(0) << setfill(' ');
// }
//}
return(true);
}
