# [seqfan] Re: Rant on Maple code

Wed Aug 12 22:16:09 CEST 2009

```[seqfan] Re: Rant on Maple code

Hello Richard!

rm> In http://list.seqfan.eu/pipermail/seqfan/2009-August/002074.html
rm> some comparisons of coding style were attempted:

Well, if I would enter your style of reply I would say
"the comparison was not attempted but was made though not
to the approval of all." But to put a ranting answer to
an rant would come close to a flame, which I do not want
to conduct.

pl> with(finance):seq(mul(cashflows([k,k,1],0),k=0..n),n=-1..22);

pl> (2) A nightmare. I did not even know that Maple comes with a
pl> package 'finance'. So I looked it up in the Maple help pages

rm> So you learned something. This is a nice point in some of the Maple
rm> implementations.

No, I did not. It would have been nice if I did.
I said this clearly.

pl> what cashflows are. It says:
pl>
pl> finance[cashflows] - present value of a list of cash flows
pl>
pl> Aha. But we are talking about the double factorial. And why
pl> does n starts at '-1'? I found no hint in the references,
pl> in the links or in the formula section which explains this
pl> implementation.

So you think this is not a valid objection? To find
some kind of mysterious code and no hints, no references
which give me the assertion that I can use this code
with confidence? For me this snippet is a candidate for
immediate deletion from the database.

rm> This does not get to the point. There hundreds of examples of this
rm> kind of code (all by Zerinvary) who is trying to demonstrate that all
rm> the polynomials (and there are many of them in the OEIS) can be written
rm> as sums of polynomials of lesser degree (to be applied recursively)
rm> and there seems to be a similar mission in the factorial domain.
rm> While this seems to be trivial, superfluous (that is: worthless) to most of
rm> us, we can look at these Maple snippets as some formulas
rm> sprung out of some undergraduate formula book, landing for some reasons
rm> not in the formula but in the coding section of the OEIS.

"This does not get to the point." Exactly. At least from the
point of view from which I look at the database.
When I use this database I am not interested what a
single person is trying to demonstrate and, as a casual user,
I am not in the position to comprehend that some special
private theory is exercised here -- I want to find
reliable, easy to check and ready to plug in snippets of code.
Everything else should take place at some other place.

pl> (4) Not really helpful. 'doublefactorial' is not implemented
pl> in the older versions of Maple. And there are many Maple V
pl> still out there just because they are not so buggy as the

rm> Clearly, (4) is the best out of the four. The reasons are :

[.. five resaons ..]

but no answer to the objection that this function is not
implemented in most versions of Maple.
The five reasons you give are all interesting points to
discuss, but all fail a priori if the function is not available.

pl> A001147 := n -> 2^n*pochhammer(1/2, n);

rm> A very doubtful attempt, and already a giant step forward
rm> to obfuscation.

Compared, for example, to

"with(finance):seq(mul(cashflows([k,k,1],0),k=0..n),n=-1..22);"?

Come on Richard, get serious.

Cheers Peter

(I suggest to continue the discussion by private mail if you desire.)

```