phase of the moon

3 definitions found

phase of the moon - WordNet (r) 2.1 (2005) :

  phase of the moon
      n 1: a time when the Moon presents a particular recurring
           appearance

phase of the moon - Free On-line Dictionary of Computing (26 May 2007) :

  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)
  

phase of the moon - Jargon File (4.4.4, 14 Aug 2003) :

  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.