Dear everyone, I am trying to figure out the specific formulation when performing C0Projection, i.e. If I define m_c0ProjectExp as following m_c0ProjectExp = MemoryManager<MultiRegions::ContField2D>:: AllocateSharedPtr(m_session,m_graph,"DefaultVar"); Then what is the specific algorithm when perform the following command(all relative options are default)? m_c0ProjectExp->FwdTrans(var,var_Coeffs); m_c0ProjectExp->BwdTrans(var_Coeffs,var_smooth); If I have a discontinuous(across element interface) distribution of var, then what has been done during the above procedure? Could anyone please recommend me some materials on this? If possible, where can I find this topic on the book "Spectral/hp Element Methods for Computational Fluid Dynamics" Thank you in advance! Best wishes, Jian Yu