message: Fixed SparseMatrix::DiagScale to work on GPU.
diff: @@ -2145,6 +2145,9 @@ void SparseMatrix::DiagScale(const Vector &b, Vector &x, double sc) const
  {
  MFEM_VERIFY(Finalized(), "Matrix must be finalized.");
  + auto bp = b.HostRead();
  + auto xp = x.HostWrite();
  +
  bool scale = (sc != 1.0);
  for (int i = 0, j = 0; i < height; i++)
  {
  @@ -2159,11 +2162,11 @@ void SparseMatrix::DiagScale(const Vector &b, Vector &x, double sc) const
  MFEM_VERIFY(std::abs(A[j]) > 0.0, "Diagonal " << j << " must be nonzero");
  if (scale)
  {
  - x(i) = sc * b(i) / A[j];
  + xp[i] = sc * bp[i] / A[j];
  }
  else
  {
  - x(i) = b(i) / A[j];
  + xp[i] = bp[i] / A[j];
  }
  break;
  }
  