computeLU() [2/5]

void DMatLUinPlace< M2::ARingRR >::computeLU ( )

inlineprivate

Definition at line 319 of file dmat-lu-inplace.hpp.

{
  if (mIsDone) return;
 
  //  std::cout << "computing LU decomposition ARingRR" << std::endl;  
  int rows = static_cast<int>(mLU.numRows());
  int cols = static_cast<int>(mLU.numColumns());
  int info;
  int min = (rows <= cols) ? rows : cols;
 
  if (min == 0)
    return;
 
  int* perm = new int[min];
  std::vector<double> copyA = make_lapack_array(mLU);
 
  dgetrf_(&rows, &cols, copyA.data(), &rows, perm, &info);
 
  if (info < 0)
    {
      // First, clean up, then throw an exception
      delete [] perm;
      throw exc::engine_error("argument passed to dgetrf had an illegal value");
    }
 
  // Now copy back to row major order
  fill_from_lapack_array(copyA, mLU);
 
  // Now place the correct permutation into mPerm
  for (int i = 0; i < min; i++)
    {
      int thisloc = perm[i] - 1;
      if (i != thisloc)
        {
          mSign = not mSign;
          size_t tmp = mPerm[thisloc];
          mPerm[thisloc] = mPerm[i];
          mPerm[i] = tmp;
        }
    }
 
  LUUtil<RingType>::computePivotColumns(mLU, mPivotColumns);
  mIsDone = true;
 
  delete [] perm;
}