Sorry, I comment not for answering question.

I want to ask a question, but I can't enter any 'Tags', but they need at least one tag.

There is not any text box where I can enter a tag.

Who can help me?

thanks!

Hi,

I asked a question before, how to shift subscript of u(i,j):

P: u[i,j] -->  u[i+1,j]

https://www.mapleprimes.com/questions/223136-How-To-Define-An-Operator

How about an arbitrary expression?

P: u[i,j]^2 v[i,j]+u[i-1,j]  -->  u[i+1,j]^2 v[i,j]+u[i,j]

thanks.

Hi, I need to calculate some discrete variational problems, but it's a hard work just by hand.

Is there any toolboxes about the discrete variational computation? Or how to design a program to do that?

In particular, I need to realize the functions:

1. the linearized operator and the adjoint operator of some expressions.

       For example:

       the linearized operator of u(n,m+1)u(n+1,m) is u(n+1,m)Tm+u(n,m+1)Tn

       the adjoint operator is u(n+1,m-1)T^(-1)m+u(n-1,m+1)T^(-1)n,

       (The latter is just the discrete Euler operator.)

      Tm, Tn is the shift operator, T^(-1) is the inverse operator of T.

2. discrete Euler-Lagrange equation.

I am not familar with the maple, please help!

Thanks.

Hi,

I want to define an operator P, which can shift the first subscript of u(i,j)

P: u(i,j)->u(i+1,j)

and similarly,

Q: u(i,j)->u(i,j+1)

I am not familiar with the commands in maple, please help!

Thanks.

Download err_subs.mw