[Maxima-discuss] integrate_use_rootsof question, was: How can I catch this error? "errcatch" doesn't do the trick.

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

On 2015-09-08, David Scherfgen <d.s...@go...> wrote:

> All we need to do is to use a different variable inside the rootsof
> expression, not the original variable of integration. This prevents the
> back-substitution at the end of the integration.
>
> Here's a possible way to do that:
>
> src/sin.lisp, line 169:
> - (($rootsof) ,qq))))
> + (($rootsof) ,(subst (make-param) variable qq)))))
>
> (%i1) integrate(1/(x^(1/3)+x+1),x),integrate_use_rootsof:true;
> (%o1) 3*'lsum((%r1^2*log(x^(1/3)-%r1))/(1+3*%r1^2),%r1,rootsof(%r2^3+%r2+1))
>
> As you see, there are now two auxiliary variables, %r1 and %r2. Maybe the
> second one should get a different prefix? I don't know if there is any kind
> of guideline for that.

Is there another way to inhibit the unwanted substitution? I think it's
better to keep the rootsof(...) expression in terms of the variable of
integration -- otherwise we would need to add a notation to rootsof to
indicate what the variable is. Also it might (or might not) look
unfamiliar to users.

> If somebody gives me the permission, I would gladly make this my very first
> Git commit to Maxima.

If you have a Sourceforge user name, I will gladly add it to the list of
developers.

best,

Robert Dodier