Hi I was trying to evaluate the rk4imp solver at large step, but not being able to do it on a fixed stepsize way. Can I truely do rk4imp with a fixed time step ?
I used the following two lines, and also put a print line in f, the time printed out have many steps between [t,t+h], Is it normal in the internal stage when solving the fixed point or still an adaptive stepsize control ? GSL_ODEIV_FN_EVAL(&sys, t, y, dydt_in); int status = odeiv2_step_apply (s, t, h, y, y_err, dydt_in, dydt_out, &sys); Lingyun On Thu, Dec 31, 2009 at 1:24 AM, Tuomo Keskitalo <[email protected]> wrote: > Hello, > > take a look at my ode-initval2 extension to GSL, it's rk4imp iterates to > convergence. Note: I'm currently working on finetuning the ode-initval2 > framework, it will soon change slightly from version 0.9. > > http://iki.fi/tuomo.keskitalo/gsl/ode-initval2/ > > On 12/29/2009 08:35 PM, Forest Yang wrote: > >> Hi All, >> >> Is there any plan for implementing convergence check in implicit >> RK4 method ? >> It seems the 2 stages Gauss points are only iterate 3 steps, without >> checking whether it is converged or not. >> Another possible way could be using the Jacobian to solve for "Y_i", >> the fixed point. >> >> The reason I care about this is, Implicit Gauss RK4 is symplectic, >> which for Hamiltonian Dynamics simulation is a very important >> property, >> it has better conservation of the first integral. >> >> >> Best regards, >> Forest. >> >> >> _______________________________________________ >> Help-gsl mailing list >> [email protected] >> http://lists.gnu.org/mailman/listinfo/help-gsl >> > > > -- > [email protected] > http://iki.fi/tuomo.keskitalo > _______________________________________________ Help-gsl mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-gsl
