Re: [Maxima-discuss] find_root how to use it

[Robert D. <rob...@gm...>]

On 2016-09-28, André Fettouhi <a.f...@gm...> wrote:

> find_root([-(1.644898582136851*10^-4*x^3+0.007402043619615831*x^2+

Well, this seems to show that your expression is a list of one or more
elements. find_root doesn't know what to do with that. Is your spline
function returning a list somehow? 

> Why isn't it evaluating it? Or am I using find_root wrong? There should be
> two solutions f(x).

Well, find_root expects the sign of f(x) to be different at the two
endpoints, and it expects exactly one root in between. My advice is to
plot the expression and look for an interval to enclose each root.

Speaking of plotting, I tried plotting the fragment which you posted,
and at least that much of it is kind of strange. You might verify that
the function looks the way you expect (strange or not).

best,

Robert Dodier