void cElHomographie::ToMatrix(ElMatrix<REAL> &  M) const
{
   M.set_to_size(3,3);
   M(0,0) = mHX.CoeffX(); M(1,0) = mHX.CoeffY(); M(2,0) = mHX.Coeff1();
   M(0,1) = mHY.CoeffX(); M(1,1) = mHY.CoeffY(); M(2,1) = mHY.Coeff1();
   M(0,2) = mHZ.CoeffX(); M(1,2) = mHZ.CoeffY(); M(2,2) = mHZ.Coeff1();
}