Re: [Help-gsl] references for rk4imp and gear2 in version 1.13

[Halasz Gabor]

Dear Mohammad,

Thank you for your answer.

You are right. But at the moment I have all the results I need for publication. 
We are writing the paper and I think it would be awful to repeat the hole 
--otherwise correct-- calculations in this phase of our work just because there 
is a newer version of a software around.

Best regards, 
Gábor

On 2017. december 10. 20:05:25 Mohammad Akhlaghi wrote:
> Dear Gábor,
> 
> You don't need root access to build and install a different version of GSL 
> (or any software) on a server. A complete description of how to do it is 
> given here:
> 
> https://www.gnu.org/software/gnuastro/manual/html_node/Installation-directory.html
> 
> Following the names in that page, to compile your own programs with your GSL 
> installation (not the server's), just add these two options to your 
> compilation command (they are described in that page).
> 
> -I/YOUR-HOME-DIR/.local/include
> -L/YOUR-HOME-DIR/.local/lib
> 
> Cheers,
> Mohammad
> 
> On December 10, 2017 7:34:32 PM GMT+01:00, Halasz Gabor <address@hidden> 
> wrote:
> >Dear Tuomo,
> >
> >Thank you for your answer.
> >
> >Actually I have found the reference for Gear's paper but never found an
> >explanation what is the difference between  gear1 and gear2 in GSL.
> >Actually all mentioning of Gear's method in new documents are similar
> >to the following one:
> >"the class of BDFs or commonly understood as Gear’s Method".
> >
> >But if it is a "class of methods" it would be nice if I can make it
> >clear which variant I have used.
> >
> >I am using GSL on a server for which I have no root access, so I can
> >not change the version as fast as I would like to publish our results.
> >But despite of the old version, gear2 is an msbdf variant and bsimp is
> >also available in this GSL version 1.13.
> >
> >Maybe there is a wider palette of suitable methods in the newer
> >versions, but I am satisfied with the old version. Two of the methods
> >provided the same results with high accuracy and these results are in
> >agreement with the expectations. 
> >
> >Other methods provided very similar results for a wide range of the
> >parameters. Usually they were faster and sometimes provided results
> >even a bit closer to the "expectations".  But they failed --including
> >rk2imp, gear1 or bsimp-- for the cases where I needed an extreme long
> >integration.
> >
> >Best regards,
> >Gábor
> >
> >
> >On 2017. december 10. 19:23:33 Tuomo Keskitalo wrote:
> >> Hi,
> >> 
> >> for rk4imp I suggest this reference:
> >> 
> >> Ascher, U.M., Petzold, L.R., Computer methods for ordinary
> >>     differential and differential-algebraic equations, SIAM,
> >>     Philadelphia, 1998. ISBN 0898714125, 9780898714128
> >> 
> >> I think those old Gear methods are based on this reference:
> >> 
> >> Gear, C.W., Numerical Initial Value Problems in Ordinary Differential
> >
> >> Equations, 1971.
> >> 
> >> However, I guess you really don't want to use those old deprecated 
> >> ode-initval methods. Instead, please updgrade to GSL version 2.4, use
> >
> >> ode-initval2, and try e.g. msbdf or bsimp methods, if your ODE system
> >is 
> >> stiff.
> >> 
> >> BR,
> >> Tuomo
> >> 
> >> On 10.12.2017 13:48, Halasz Gabor wrote:
> >> > Hello,
> >> > 
> >> > I have a problem with finding proper references and descriptions
> >for some methods I have used for solving ODEs with GSL version 1.13.
> >> > For the stepping functions gear1(2) the info page and the manuals
> >only contain the following simple description: M=1(2) implicit Gear
> >method.
> >> > 
> >> > I am especially interested in methods rk4imp and gear2 as all the
> >other available ones in version 1.13  was not working properly for my
> >ODEs.
> >> > 
> >> > Best regards,
> >> > Gábor
> >> > 
> >> > 
> >> > 
> >> > 
> >> 
> >> 
> >> 
> 
>