= P =
1. [scientific computation] Used of a
data set that is grossly atypical of normal expected input, esp.
one that exposes a weakness or bug in whatever algorithm one is
using. An algorithm that can be broken by pathological inputs may
still be useful if such inputs are very unlikely to occur in
practice. 2. When used of test input, implies that it was
purposefully engineered as a worst case. The implication in both
senses is that the data is spectacularly ill-conditioned or that
someone had to explicitly set out to break the algorithm in order
to come up with such a crazy example. 3. Also said of an unlikely
collection of circumstances. "If the network is down and comes up
halfway through the execution of that command by root, the system
may just crash." "Yes, but that's a pathological case." Often
used to dismiss the case from discussion, with the implication that
the consequences are acceptable, since they will happen so
infrequently (if at all) that it doesn't seem worth going to the
extra trouble to handle that case (see sense 1).
--The Jargon File version 4.3.1, ed. ESR, autonoded by rescdsk.