{
  scalarField magU = mag(U.internalField() - U.oldTime().internalField());

  forAll(magU, cellI) {
    if (magU[cellI] < SMALL) {
      magU[cellI] = SMALL;
    }
  }

  relativeResidual =
      gMax
      (
          mag
          (
              U.internalField()
              - U.prevIter().internalField()
          )
          /magU
      );
}
