Higher order difference expressions

[karaali]

Hello. I need finite difference expression of sixth order derivative in h^2. I derived it using Mathematica 6 but when I use the expression there appear a problem. Solution is wrong. I check everythin and realized that only i m not sure about that expression. I ll be appreciated if you help. Thanks in advance.

 

[HallsofIvy]

I don't know what you mean by " sixth order derivative in h^2".

 

[karaali]

Hi. Let me explain.

I have a differential equation and try to solve it using finite difference method. Differential equation has sixth order derivative of dependent variable. So; i need difference expression for that derivative. "h" is the step size and saying " sixth order derivative in h^2" i mean the order of the error is square of step size.( O(h²) )