### [deal.II] A simple column buckling problem

Dear friends, I've recently stepped into dealii. While I appreciate it's capabilities and so on.. I want a starer code for my simple structural mechanics problems. Can someone give me a simple code for a rectangular column buckling problem in 2D or 3D, It's an eigenvalue problem... Thanks for

### Re: [deal.II] What is the first and second index of the gradient tensor

Dear Dr.Bangerth, I found it just before, it is on the page of FEValuesView ( https://www.dealii.org/current/doxygen/deal.II/classFEValuesViews_1_1Vector.html). Thank you very much! Best regards, Yuesu On Mon, Sep 7, 2020 at 11:00 PM Wolfgang Bangerth wrote: > On 9/7/20 6:21 PM, yuesu jin

### Re: [deal.II] Periodic boundary conditions in Newton's method

On 9/7/20 6:40 PM, Jimmy Ho wrote: I have a general question regarding the application of periodic boundary conditions in Newton's method when solving nonlinear equations. Should the periodic constraint be applied to the incremental Newton update, or directly to the total solution vector?

### Re: [deal.II] What is the first and second index of the gradient tensor

On 9/7/20 6:21 PM, yuesu jin wrote:   I want to contract the gradient tensor with another vector, such as T_ij*n_j, the gradient tensor is d_j u_i (d is the partial differential operator). I am wondering what is the first index of gradient tensor, i or j? I believe it is T_ij = d_j u_i I

### [deal.II] Periodic boundary conditions in Newton's method

Hi All, I have a general question regarding the application of periodic boundary conditions in Newton's method when solving nonlinear equations. Should the periodic constraint be applied to the incremental Newton update, or directly to the total solution vector? Thanks in advance for any

### [deal.II] What is the first and second index of the gradient tensor

Dear all, I want to contract the gradient tensor with another vector, such as T_ij*n_j, the gradient tensor is d_j u_i (d is the partial differential operator). I am wondering what is the first index of gradient tensor, i or j? Thank you ! Best regards, Yuesu -- Yuesu Jin, Ph.D student,