[seqfan] Re: Sequences that use '-1' to indicate 'impossible'.

David Wilson davidwwilson at comcast.net
Wed Sep 23 23:33:36 CEST 2015


How about adding an domain sequence D that includes just the values on which sequence A is defined. Then change A to include just those values where it is defined.

> -----Original Message-----
> From: SeqFan [mailto:seqfan-bounces at list.seqfan.eu] On Behalf Of Charles
> Greathouse
> Sent: Wednesday, September 23, 2015 10:05 AM
> To: Sequence Fanatics Discussion list
> Subject: [seqfan] Re: Sequences that use '-1' to indicate 'impossible'.
> 
> There are cases where it would be nice to have a sigil for "undefined", "does
> not exist", "positive infinity", etc. But I think there's too much code relying on
> the entries to be strictly numeric for this to happen.
> 
> Charles Greathouse
> Analyst/Programmer
> Case Western Reserve University
> 
> On Wed, Sep 23, 2015 at 8:12 AM, Sidney Cadot <sidney at jigsaw.nl> wrote:
> 
> > Hi,
> >
> > Some sequences use '-1' to indicate that a certain entry does not
> > exist, e.g. A154852 and A237584.
> >
> > Should such sequences be considered signed (kw:sign) or unsigned
> (kw:nonn)?
> >
> > Wouldn't it be more appropriate to allow an explicit "null" value in
> > such cases?
> >
> > Regards, SIdney
> >
> > _______________________________________________
> >
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> >
> 
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