[seqfan] Re: Proposal for better presentation of some sequences with complex numbers

Maximilian Hasler maximilian.hasler at gmail.com
Fri May 27 23:25:10 CEST 2011

With my apologies to sequence fans who are rather interested in
mathematics than in technical details (which should be the normal
case...), but lacking a dedicated mailing list:

Another earlier suggestion of mine which could realize the same functionality,
and might be easier to implement, was that of extended keywords:

Initially, I suggested that the kw TABF ("fuzzy table") could have an
optional argument specifying the sequence giving the row lengths, e.g.

oeis.org/A036039 : 	Triangle of multinomial coefficients read by rows.

would have keyword  "tabf(A000004)"   or "tabf(000004)"   or "tabf(4)"
  or "tabf000004"
and clicking on this kw would display the sequence as formatted table
(using e.g. Wolfdieter Lang's script [which is no more linked via the
"tabf" KW !?]).

This would be extremely easy to implement, maybe one single line in
the output formatting script, and no change at all to the database
(assuming that the kw length of 4 characters isn't hardwired anywhere)
[except for progressively completing the extended keywords].

In the same way one could add keywords "real(NNN)" and "imag(MMM)"
which would mean that this is the sequence of real parts (resp.
imaginary parts) of a complex sequence c(n) = MMM(n)+NNN(n)*i , and
again, clicking on the link (or without clicking on it) could display
it in the "complex" way.
Here again, a simple link could be coded in a single line;
alternatively (or additionally), javascript for a Popup window for the
adequate display (just like some themes of wikimedia allow to preview
the content of the target of a link by just pointing the mouse on it)
could also be added without significant code change.

Of couse the same applies for fractions, using e.g. (extended)
keywords "numer(NNN)" and "denom(MMM)".



On Fri, May 27, 2011 at 4:42 PM,  <franktaw at netscape.net> wrote:
> Some time back, I proposed adding F numbers, which would provide a standard
> way to show not only fractions and complex numbers, but also irregular
> tables, two-way infinite sequences, sequences defined on fractions and
> complex numbers, and a number of other things. The reaction at the time was
> underwhelming, but I still think it's a good idea. Note that with this
> proposal, one would be able to search for these things as well.
> The basic idea is to have a database with definitions, like
> "A000010/A000027". This could include comments, formulae, everything except
> actual values and (in some cases) offsets; the sequence contents, including
> b-file equivalents, would then be automatically generated.
> Implementing this would be a major project, I admit.
> Franklin T. Adams-Watters
> -----Original Message-----
> From: N. J. A. Sloane <njas at research.att.com>
> Charles said:
>> I think that it would be a good idea to have something that can format
> fractions and complex numbers from two sequences, just like we can
> show tables for tabl sequences and plot2 for any pair.
> Great idea! Maybe you could discuss it with Russ Cox?
> Neil
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