[seqfan] Re: Offsets of cons sequences

Richard Mathar mathar at strw.leidenuniv.nl
Sat Aug 22 15:10:54 CEST 2009

cg> But whatever is decided, I'd be happy to pitch in on the conversion
cg> effort.  Maybe someone can compile a list and split up the work so
cg> there's no duplication?

Once there is a defined format, one can essentially run a pair of

 read("transforms3") ;
 L := BFILETOLIST("bxxxxx.txt") ;   # read file into a list
 LISTTOBFILE("bxxxx.txt",L,newoffsethere) ; # create file from list with offset

in Maple for each file to be converted.  transforms3 is
the library in http://www.strw.leidenuniv.nl/~mathar/progs/transforms3 .

Another point: the first column in each b-file (for constants and also for the
other sequences) is of course redundant, as long as these files contain
only consecutive values. To store that information is not needed if
the offset (a single number) is easily available. Each ASCII editor 
has some sort of line enumeration capability. (vi users will use the "j"
or ":" to move to relative or absolute line numbers, for example. less -N
will enumerate lines by default. I suspect that even on Gate's systems such
a thing exists.) The current b-file format with explicit
tagging of each value makes only sense if "holes" are allowed, such as in
http://www.strw.leidenuniv.nl/~mathar/progs/b007504+.txt or
as in the recent tabulations of solutions to some modular equations.
   From a programmer's point of view, keeping redundant information at different
places is a nightmare, because it basically means that each read-attempt
is forced to check for incompatibilities, accumulating data from various
forms of databases and formats. My experience is that "ordinary" people
want to have just the opposite: they want to have values stored at least twice
or even more often at different places "for safety," and they leave it to 
the nightly working hours of the programmers to figure out how this all can be
kept aligned.


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