the diff procedure

[Brocci, R. A.]

To GNU or the diff maintainer(s),
 
Are there efforts underway to imbed numerical differerence capability --
e.g., as in GNU's numdiff procedure -- in the basic diff procedure?
 
If so, what is the status?
 
If not, and to your knowledge, has such an effort even/ever  been
discussed?
 
Assuming you're not familar with numdiff, and I've only done a limited
read of its Users Manual, it supposedly has the ability to numerically
compare the illustrative diff -y record
 
    nvf1 ... nvfN   |   nvf1 ..  nvfN
 
where the nvfF string indicates a numeric value in field F. For example,
if nvF1 in the two files is 1.00001 and 1.000001 respectivley, and all
other nvfF's are the same, this record would be issued by diff.
 
However, among the numdiff options are an absolute and relative
tolerance for comparing the nvfF entries, and therefore depending on
what I provide for these values -- or perhaps on what their default
values may be -- this record may or may not be reported as a difference.
 
Note: It is my understanding that diffs between "Nan's" are reported as
usual.  For example, if what I've called nvf2 is 'A123' and 'a123'
respectively, then this record would appear as a difference unless of
course I used the -i option.
 
Note: numdiff and its ndiff predecessor (I think) from the University Of
Utah CS Dept. have problems when the files have a disparate number of
records leading upto the above illustrative record. and may also have
problems if the number of fields differ as well.
 
I have recommended importing numdiff and maybe ndiff for use at my
facility, and that is why I've asked the above questions.
 
Note: From a "calibration" point of view, our newest Linux OS (from
SuSE) has diff version 2.8.7, and it is difficult at best to get our
systems personnel to download a newer/better version, and then do a
rebuild, etc. (It is version 2.8.4 on our older Linux OS machines. And,
our oldest (vendor-specific Unix OS?) machines are old enough to not
support the --help and/or --version options.)
 
Thanks for your time.
 
 
 
Tony Brocci    06 Mar 2009
KAPL
POB 1072,  Mail Stop 122
Schenectady, NY  12301
518-395-6682
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