[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

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

From: Halasz Gabor
Subject: Re: [Help-gsl] references for rk4imp and gear2 in version 1.13
Date: Sun, 10 Dec 2017 19:34:32 +0100
User-agent: KMail/4.14.10 (Linux/4.4.92-18.36-default; KDE/4.14.25; x86_64; ; )

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 
"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,

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
> > 
> > 
> > 
> > 

reply via email to

[Prev in Thread] Current Thread [Next in Thread]