Martin Rubey wrote:
>
> Martin Rubey <[email protected]> writes:
>
> > Hi there!
> >
> > I wanted to integrate a second order nonlinear differential equation,
> > and fricas responded with the error "no a linear diffeq"... Is just the
> > error message misleading, or is it a bug?
>
> I should add: ")tr" shows that solve indeed calls the solver for
> non-linear equations, as I wanted it too.
>
AFAICS currently only nonlinear differential equations that FriCAS can
solve are of first order. The 'parseODE' routine notices that the
equation is of higher order, so tries to treat it a a linear equation.
'parseLode' correctly determines that the equation is nonlinear
and reports error. Yes, error message could be better.
BTW: 'parseODE' is buggy, it can get confused on more complicated
differential equations (but on your one it works as designed).
I have better routine for parsing differential equations, it
can also recognise some classes of "easily solvable" equations
that current solver can not handle (but after recognising given
class one alse needs an actual solver).
--
Waldek Hebisch
[email protected]
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