Hello,
rk2imp (among other implicit methods) in ode-initval2 uses a modified
Newton iteration instead of old functional iteration in solving the
system of non-linear equations. E.g. for stiff problems Newton iteration
is quite more powerful. Because of that, the ODE-solver can use larger
step sizes. Newton iteration converges with larger step sizes, while
functional iteration does not.
On 12/01/2011 08:42 PM, Farkas, Illes wrote:
Hi,
I just tested the speed of rk2imp with the simple harmonic oscillator
(dx/dt=-y, dy/dt=x). In the first test I used gsl_odeiv_step/control/evolve
(does *not* use Jacobian) and in the 2nd test I used
simply gsl_odeiv2_driver (uses Jacobian). With the same parameters the
first version ran for 26s and the second version finished below 1s. Is this
test wrong? Or is there really such a big difference?
Thanks
Illes
_______________________________________________
Help-gsl mailing list
Help-gsl@gnu.org
https://lists.gnu.org/mailman/listinfo/help-gsl
--
tuomo.keskit...@iki.fi
http://iki.fi/tuomo.keskitalo
_______________________________________________
Help-gsl mailing list
Help-gsl@gnu.org
https://lists.gnu.org/mailman/listinfo/help-gsl
