[seqfan] Re: Chewing an old bone
Charles Greathouse
charles.greathouse at case.edu
Tue Oct 25 03:02:20 CEST 2011
Conceivably, A039834 would be an example, as it's useful to see that
the absolute value of the ratio of successive terms is approximately
constant. But for the most part I think qlog gives everything log abs
gives and more.
Charles Greathouse
Analyst/Programmer
Case Western Reserve University
On Mon, Oct 24, 2011 at 8:21 PM, David Applegate <david at research.att.com> wrote:
>> I really hope that the qlog plot will remain *supplementary* to the
>> log plot (for large signed sequences), and will not replace it. Each
>> of these plots can be the more useful one depending on applications.
>
> Do you have an example of when plotting log(|a(n)|+1) or
> log(a(n)+1) is more informative than plotting qlog(a(n))?
>
> David Applegate
>
>> From seqfan-bounces at list.seqfan.eu Mon Oct 24 20:08:24 2011
>> Date: Mon, 24 Oct 2011 17:08:13 -0700
>> From: =?ISO-8859-1?Q?Beno=EEt_Jubin?= <benoit.jubin at gmail.com>
>> To: Sequence Fanatics Discussion list <seqfan at list.seqfan.eu>
>> Subject: [seqfan] Re: Chewing an old bone
>
>> > Currently, the qlog plot is supplementary to the log plot, if I understand Russ
>> > Cox correctly, this situation is provisional, and if the qlog plot works out, it
>> > will replace the log plot.
>
>> I really hope that the qlog plot will remain *supplementary* to the
>> log plot (for large signed sequences), and will not replace it. Each
>> of these plots can be the more useful one depending on applications.
>
>> On Mon, Oct 24, 2011 at 6:48 AM, David Wilson <davidwwilson at comcast.net> wrote:
>> > From looking at the old code, the scatter plot scale was as follows:
>> >
>> > For small graphs, a(n)
>> > For large nonnegative graphs, log(a(n)+1)
>> > For large negative graphs, log(|a(n)|+1)
>> >
>> > Except for graph title, this is equivalent to
>> >
>> > For small graphs, a(n)
>> > For large graphs, log(|a(n)|+1)
>> >
>> > The criterion for deciding what is a large graph is complicated, based
>> > on a sample of five elements. Personally, I would have chosen a log plot
>> > based on some simpler criterion, say if |a(n)| or max(a)-min(a) exceeds
>> > some constant N.
>> >
>> > Currently, the qlog plot is supplementary to the log plot, if I understand
>> > Russ
>> > Cox correctly, this situation is provisional, and if the qlog plot works
>> > out, it
>> > will replace the log plot. By this I mean that a(n) scatterplot will appear
>> > when
>> > it now does, the qlog scatterplot will appear when the log plot now does.
>> >
>> >
>> > I don't think it is much of a decision: look at, say, A000055, apart from
>> > titles,
>> > the log and qlog plots are visually identical for nonnegative sequences. If
>> > you
>> > then look at, say, A055615, you see the advantage of the qlog plot over the
>> > log plot re showing negative values.
>> >
>> >
>> > On 10/23/2011 11:28 PM, Benoît Jubin wrote:
>> >>
>> >> Is it normal that there is a scatter plot of qlog for every signed
>> >> sequence, even when there is no scatter plot of log (because the
>> >> sequence assumes only small values in the displayed interval; see
>> >> https://oeis.org/A002321/graph)?
>> >>
>> >> Also, this is nitpicking, but there is some discrepancy in the titles
>> >> of all the graphs: "Pin plot of Axxxxx" and "Scatterplot of Axxxxx(n)"
>> >> (one or two words, and with or without argument).
>> >>
>> >> Thanks for the addition of the qlog graphs, and I agree with previous
>> >> posts that it should stay "in addition to" log, and not "instead of".
>> >>
>> >> Benoit
>> >>
>> >> On Sun, Oct 23, 2011 at 5:00 PM, David Wilson<davidwwilson at comcast.net>
>> >> wrote:
>> >>>
>> >>> On 10/23/2011 5:23 PM, Russ Cox wrote:
>> >>>>
>> >>>> Sounds good. I have installed the graph:
>> >>>>
>> >>>> https://oeis.org/A103718/graph
>> >>>>
>> >>>> Russ
>> >>>>
>> >>> Thank you all for putting up with me regarding this.
>> >>>
>> >>>
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>> >>>
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>> >
>> >
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