[Help-gsl] rk2imp speed in odeiv vs odeiv2

[Farkas, Illes]

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