[Tutor] hi

[Oscar Benjamin]

On 20 August 2013 13:49, Vick <vick1975 at orange.mu> wrote:
>
> From: Oscar Benjamin [mailto:oscar.j.benjamin at gmail.com]
>
>> Well just send me some tutorial on how to build and obtain the
>> coefficients for the butcher tableau for the RK4 as an example, and
>> after I've mastered it, I'd give the dopri8 a shot.
>
> I am up for it so I'll see if I can find time to write a script that shows
> how to do it.
>
> [Vick] Hope you've had the time to code it. I'm waiting for it.

Sorry, I haven't found the time yet. It is still on my todo list though!

> By the way your code for the Adams-Moulton coefficients are actually the
> Adams-Bashforth ones and so I copied it and modified the copy to have the
> Adams-Moulton coefficients as well. This means that I have now an nth-order
> predictor-corrector method to solve for ODEs.

Oh sorry. That'll be a cut and paste error. My code lives in a private
software library that I keep meaning to release on PyPI but it's not
ready for public consumption in quite a number of ways.

I'm glad that you worked it out though. You''ll probably understand
what I mean now when I say that the AM or AB integrators need a
secondary algorithm to bootstrap. The accuracy of the subsequent AM/AB
method depends on the accuracy of that step. In the worst case you can
just use rk4 with a very small time-step for this bit though.


Oscar