Hi Ehsan I believe that you should use Modified_B basis from GaussRadauMAlpha1Beta0 quadrature. I am also assuming that you are using prism elements for the mesh? https://doc.nektar.info/userguide/5.0.0/user-guidese7.html Best, Jacques ________________________________ From: nektar-users-bounces@imperial.ac.uk <nektar-users-bounces@imperial.ac.uk> on behalf of Ehsan Asgari <eh.asgari@gmail.com> Sent: Monday, May 15, 2023 9:29 AM To: nektar-users <nektar-users@imperial.ac.uk> Subject: [Nektar-users] potential bug with detailed expansion This email from eh.asgari@gmail.com originates from outside Imperial. Do not click on links and attachments unless you recognise the sender. If you trust the sender, add them to your safe senders list<https://spam.ic.ac.uk/SpamConsole/Senders.aspx> to disable email stamping for this address. Dear All, When I use a "Modfied" type for expansions everything works fine. But if I specify the expansions in detailed mode: <E COMPOSITE="C[30011]" BASISTYPE="Modified_A,Modified_A,Modified_A" NUMMODES="7,7,7" POINTSTYPE="GaussLobattoLegendre,GaussLobattoLegendre,GaussRadauMAlpha1Beta0" NUMPOINTS="8,8,7" FIELDS="u,v,w" /> <E COMPOSITE="C[30011]" BASISTYPE="Modified_A,Modified_A,Modified_A" NUMMODES="6,6,6" POINTSTYPE="GaussLobattoLegendre,GaussLobattoLegendre,GaussRadauMAlpha1Beta0" NUMPOINTS="7,7,6" FIELDS="p" /> Then I get a bunch of errors: [xxx518:29773] *** Process received signal *** [xxx518:29773] Signal: Segmentation fault (11) [xxx518:29773] Signal code: Address not mapped (1) [xxx518:29773] Failing at address: 0x27b2000 I have a fully hex mesh. Could you kindly point out if something is wrong with the way I specify the expansions? Kind regards syavash