Re: [Maxima-discuss] rkf45 share

[Michel T. <ta...@lp...>]

Le 18/01/2017 à 15:46, Michel Talon a écrit :
> First b line
> 0.1185185185185185 0 0.5189863547758284 0.5061314903420167 −0.18	
> 0.03636363636363636
> I don't know where these numbers appear, the last one is in truc_error.
>
> second b line
> 0.1157407407407407 0 0.5489278752436647 0.5353313840155945 <-- 46 bfloat
> -0.2	0

In fact i have seen in 
https://en.wikipedia.org/wiki/Runge%E2%80%93Kutta_methods
that to estimate the error one substracts the two b lines. But then
0.1185185185185185-0.1157407407407407=0.0027777777777..
0.5189863547758284-0.5489278752436647=- 0.0299415204678..
0.5061314903420167-0.5353313840155945=- 0.02919989367357789 etc.
which are all the numbers  appearing in trunc_errors.
So i think one can safely say that rkf45.mac is correct.


-- 
Michel Talon