Sorry to clog your inbox. In my previous email I forgot to tell that I used interpolator_on_mesh_fem to get the gradient and hessian. Basically I would like the get the first derivative and second derivative of the displacement field at some points. I understand that the gradient is definitely discontinuous across elements so we have to use a discontinuous fem as the targeted fem if the compute_gradient() is used. But I am not sure about how the gradient and hessian is calculated when calling interpolator_on_mesh_fem.eval(...) and .eval_hess(...). As I said, if the linear element is used, are those results still correct? Thanks.
Regards, Wen On Tue, Feb 11, 2014 at 9:55 AM, Wen Jiang <[email protected]> wrote: > Dear all, > > I tried to calculate the second derivative in getfem using compute > hessian. For linear elements, the second derivative of the shape function > should be zero but it seems that the results of hessian computed in getfem > is not zero. Could you tell me how is the hessian computed in getfem for > linear elements? Thanks. > > Regards, > Wen >
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