On 10/14/2018 11:57 AM, Yuxiang Wang wrote: > > While I can use the shape_grad function to get the gradient of the shape > function with respect to the real cell coordinates, would there be a way to > get the shape_grad with respect to the reference natural coordinates? For > example, for shell element (that I'm working on), I have the global > coordinates (x, y, z) for a point and also a natural coordinate system (r, s, > t). > > One possibility is that I can use the chain rule and the jacobian matrix to > get that value, but it'll be very computationally inefficient. Could anyone > please help?
I think you are asking for the *unmapped* shape functions as they are defined on the reference cell. That's something you can get from the finite element itself via the FiniteElement::shape_grad() function or its implementation in derived classes. The gradient of the shape functions mapped to a particular cell in a mesh can be obtained via FEValues::shape_grad(), which I think is what you are referring to above. Best W. -- ------------------------------------------------------------------------ Wolfgang Bangerth email: [email protected] www: http://www.math.colostate.edu/~bangerth/ -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
