Question about rk4



On 11-07-2013 21:12, Karl-Dieter Crisman wrote:
> Can someone help me with this error?  I have a feeling there is 
> something silly I'm missing in the syntax.  Thanks!
>
> (%i1) rk(['R(t)+'J(t),'R(t)+'J(t)],['R(t),'J(t)],[1,1],[t,0,10,0.1]);

The second argument must be a list of variables; it cannot be 
['R(t),'J(t)].
Since the command you show is (%i1), I'm guessing that you meant that R 
and J are two functions that depend on t to be found numerically. If 
that is the case, there is no need to specify the dependence on t; just 
use:

result: rk(['R+'J,'R+'J], ['R,'J], [1,1], [t,0,10,0.1])$

Have you already seen the manual for rk? 
(http://maxima.sourceforge.net/docs/manual/en/maxima_22.html#SEC111)

Regards,
Jaime