[MITgcm-support] FLT package

[fancer fancer]

Hi Andreas,
Thanks for the quick reply and answers.

Have you published results of your work somewhere? Could you give a link to
yours articles, which concern Lagrangian trajectories calculating?

I have attached the simple project, which simulates kind of pre-blow up
situation, when internal velocity becomes extremely huge. I've just
explicitly added huge velocity in data file. The flt package has been
activated too. If you build it and run, you will see the segmentation fault
error. As I already wrote It occurs in flt package. I guess it would be
reasonable to add some check of predicted i and j indexes, which is passed
to the FLT_TRiLINEAR().

Cheers,
Sergey

On Wed, Jun 13, 2012 at 11:46 AM, Andreas Klocker <aklocker at mit.edu> wrote:

>  Hi Sergey,
>
> You have not found any comprehensive documentation because there is
> none...so far...I've been using the flt package over the last two years and
> fixed a few things which I needed for my work but haven't written any
> documentation - i should probably do that...unless anyone else is keen ;)?
>
> re comparison with other codes: I've compared trajectories with different
> advection codes written by different people in Matlab. The results were
> very similar (but that was only done in 2D). I've calculated trajectories
> in 3D and results look very reasonable...but I have to  look into it in
> more detail to be 100% happy with it.
>
> I must admit I've never had a segmentation fault error using the flt
> package...
>
> cheers,
> Andreas
>
>
> On 13/06/12 17:26, fancer fancer wrote:
>
> Dear mitgcm developers,
>
>  I am trying to run our 3D internal waves numerical experiments with flt
> package using. It runs well and even results look quite reasonable. But
> still I have few questions:
>
>  I have not found any comprehensive documentation about the package,
> source code is only one. According to the source code the kernel of package
> is 2nd and 4d order Runge-Kutta algorithm to solve ODE and linear
> interpolation to find velocity in the middle of neighbouring array indexes.
> But I have not got the purpose of additional functionality, such as up and
> down movement of particles. Is there any comprehensive document, which
> explains theoretical base of flt package?
> I found README.flt, which looks obsolete. Isn't it? For example, kpart has
> to be initialized by vertical position in coordinate units, but README says
> that it is actual level. Is it the same or not?
>
>  In addition I have not found any publications, which concern numerical
> experiments using MITgcm and pkg/flt. Are there such articles? Does
> somebody compare results, which are got from the flt package, with
> trajectories from another packages, for example, TRACMASS?
>
>  And finally I have found the segmentation fault error in case of using
> FLT package, which occurs if the main model is near to blow up, when
> velocity is extremely high.
> The error occurs in the FLT_TRILINEAR() subroutine during actual uu
> calculating. In this case horizontal indexes, which is passed to the
> function, become extremely big. I guess, that such behavior can be related
> with package limitation. But still segfault error is not well way of
> program working, is it? May be it is reasonable to add some check of array
> indexes in the FLT_REUNGE4() subroutine at least in the 2nd, 3d and 3th
> steps?
>
>  Yours Faithfully,
> Sergey. V. Semin
>
>
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