Re: [Maxima-discuss] how to perform symbolic math with continued fractions

[Stavros M. (Σ. Μ. <mac...@al...>]

By the way, the horrible cf([...]*[...]) hack has also been very buggy for
the past 6 years. See https://sourceforge.net/p/maxima/bugs/3448/

The bug was introduced by "Apply continued fraction patch attached to bug
report # 3431927." in 2012. But I can't find that bug report on sourceforge
-- where are older bugs archived?

           -s

On Fri, Jun 29, 2018 at 1:10 PM Stavros Macrakis (Σταῦρος Μακράκης) <
mac...@al...> wrote:

> The cf group of functions is a *horribly designed hack*.
>
> The hack of supporting [...]*[...] within the cf function is an
> abomination which wrecks referential transparency:
>
> qq: [2,3]*[4,5] => [8,15]    (with listarith: true, the default)
> cf(qq) => [8,15]
> cf([2,3]*[4,5]) => [9,1,4]
>
>
> It is also an abomination because it only supports * and not / and integer
> ^.
>
> It is also an abomination because it gives incorrect results when there's
> more than one repeating cf:
>
>      cf(sqrt(2)*sqrt(5)) => [3,2,1,2]
>      cf(sqrt(10)) => [3,6]
>
> For that matter, it is an abomination that cf(sqrt(...)) doesn't indicate
> in any way that the result repeats, or what the repeating group is.
>
> As for performing cf manipulations symbolically, what do you have in mind?
>
> In particular, what is cf([a]/[0,b]) == cf(a/b)? After all, cf(5/5) = [1],
> cf(5/7) = [0,1,2,2], cf(5/11) = [0,2,5], cf(5/13) = [0,2,1,1,2], cf(5/15) =
> [0,3], etc. Not even the length is constant.
>
>
>
>
>
> On Fri, Jun 29, 2018 at 8:09 AM Hugo Coolens <hug...@gm...>
> wrote:
>
>> Is it possible to perform symbolic math with continued fractions?
>> If I try something like this:
>> cf([a,b,c]);
>> maxima answers with
>> Maxima encountered a Lisp error: Condition in MACSYMA-TOP-LEVEL [or a
>> callee]: INTERNAL-SIMPLE-TYPE-ERROR: $C is not of type NUMBER:
>>
>> can I tell maxima a,b and are of type NUMBER?
>>
>> kind regards,
>> Hugo
>>
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