| slovo | definícia |
phase of the moon
(encz) | phase of the moon,fáze měsíce Clock |
phase of the moon
(wn) | phase of the moon
n 1: a time when the Moon presents a particular recurring
appearance |
phase of the moon
(foldoc) | phase of the moon
Used humorously as a random parameter on which something is
said to depend. Sometimes implies unreliability of whatever
is dependent, or that reliability seems to be dependent on
conditions nobody has been able to determine. "This feature
depends on having the channel open in mumble mode, having the
foo switch set, and on the phase of the moon."
See also heisenbug.
True story: Once upon a time there was a bug that really did
depend on the phase of the moon. There was a little
subroutine that had traditionally been used in various
programs at MIT to calculate an approximation to the moon's
true phase. GLS incorporated this routine into a Lisp
program that, when it wrote out a file, would print a
timestamp line almost 80 characters long. Very occasionally
the first line of the message would be too long and would
overflow onto the next line, and when the file was later read
back in the program would barf. The length of the first
line depended on both the precise date and time and the length
of the phase specification when the timestamp was printed, and
so the bug literally depended on the phase of the moon!
The first paper edition of the Jargon File (Steele-1983)
included an example of one of the timestamp lines that
exhibited this bug, but the typesetter "corrected" it. This
has since been described as the phase-of-the-moon-bug bug.
[Jargon File]
(1995-02-22)
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phase of the moon
(jargon) | phase of the moon
n.
Used humorously as a random parameter on which something is said to depend.
Sometimes implies unreliability of whatever is dependent, or that
reliability seems to be dependent on conditions nobody has been able to
determine. “This feature depends on having the channel open in mumble mode,
having the foo switch set, and on the phase of the moon.” See also {
heisenbug}.
True story: Once upon a time there was a program bug that really did depend
on the phase of the moon. There was a little subroutine that had
traditionally been used in various programs at MIT to calculate an
approximation to the moon's true phase. GLS incorporated this routine into
a LISP program that, when it wrote out a file, would print a timestamp line
almost 80 characters long. Very occasionally the first line of the message
would be too long and would overflow onto the next line, and when the file
was later read back in the program would barf. The length of the first
line depended on both the precise date and time and the length of the phase
specification when the timestamp was printed, and so the bug literally
depended on the phase of the moon!
The first paper edition of the Jargon File (Steele-1983) included an
example of one of the timestamp lines that exhibited this bug, but the
typesetter ‘corrected’ it. This has since been described as the
phase-of-the-moon-bug bug.
However, beware of assumptions. A few years ago, engineers of CERN
(European Center for Nuclear Research) were baffled by some errors in
experiments conducted with the LEP particle accelerator. As the formidable
amount of data generated by such devices is heavily processed by computers
before being seen by humans, many people suggested the software was somehow
sensitive to the phase of the moon. A few desperate engineers discovered
the truth; the error turned out to be the result of a tiny change in the
geometry of the 27km circumference ring, physically caused by the
deformation of the Earth by the passage of the Moon! This story has entered
physics folklore as a Newtonian vengeance on particle physics and as an
example of the relevance of the simplest and oldest physical laws to the
most modern science.
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