Hi Ashok, I am not sure if anyone else responded to this. Did we manage to answer any of this in our chat? There is an index array ExpList->GetCoeff_Offset(e) which gives an integer offset of the global list from GetCoeffs() to tell you where element ‘e’ starts. (There is a similar GetPhys_Offset(e) if you want to get the phys point location for element ‘e’). Cheers, Spencer. On 7 Feb 2016, at 23:53, ashok jallepalli <ash.nani@gmail.com<mailto:ash.nani@gmail.com>> wrote: Hi everyone, I currently working on a project and would like to do the following task and need some guidance. (1) Read an .fld file. (2) Load it into vector fields into expansions (exp_u, exp_v, exp_w) (3) Loop through each element in the mesh and do some processing in it and store the result in a new expansion. I have a problem in step (3). I am able loop through each expansion but unable to understand how should I retrieve coefficients for each element. Array<OneD,NekDouble> gcoeff = exp_u->GetCoeffs() * This gets me the coefficients of whole expansion. How do I match coefficients which belong to each element. These two statements used in the code seem to reorder the coefficients in the expansion, Can someone explain what they are doing. Exp_u->GlobalToLocal() Exp_u->LocalToGlobal() Would any of these functions reorder coefficients elementwise. So that I use access element[i]'s coefficients as gcoeff[I*numOfCoeffPerEle]. Ashok. Spencer Sherwin McLaren Racing/Royal Academy of Engineering Research Chair, Professor of Computational Fluid Mechanics, Department of Aeronautics, Imperial College London South Kensington Campus London SW7 2AZ s.sherwin@imperial.ac.uk<mailto:s.sherwin@imperial.ac.uk> +44 (0) 20 759 45052