The basic problem seems to be that quad_qagi returns error codes (fourth
element of the return value) instead of following standard Maxima
conventions and throwing an error. Useful behavior in some contexts, but
not in plotting....
-s
On Wed, Aug 28, 2013 at 2:15 PM, Raymond Toy <toy.raymond at gmail.com> wrote:
> >>>>> "Robert" == Robert Dodier <robert.dodier at gmail.com> writes:
>
> Robert> On 2013-08-28, Raymond Toy <toy.raymond at gmail.com> wrote:
> >> I think it would be nice if maxima indicated that somehow instead of
> >> just returning a noun form. Users should have to trace internal
> >> functions to figure that out.
>
> I meant "shouldn't have to", of course.
>
> Robert> Agreed. I wonder if Maxima can distinguish integrands which
> don't
> Robert> evaluate to a number but which might (e.g. unbound variable),
> from
> Robert> those which can't (e.g. floating point error), and print
> different
> Robert> messages for those.
>
> I think this is all buried in coerce-float-fun. For gcl, any errors
> cause the function to return T. For other lisps, we do distinguish
> between an arithmetic-error and a maxia-$error, but return T in both
> cases anyway.
>
> I'm not sure what the best way for coerce-float-fun to distinguish
> between the two cases. And in any case, gcl can't so that seems not
> an option.
>
> For the quad routines, I think the best we can do now would be to
> detect a non-numerical result and signal a maxima error.
>
> Ray
>
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