Metric (analysis)
Revision as of 08:26, 8 August 2009 by JBL (talk | contribs) (moved Metric (set theory) to Metric (analysis): Set theory? Gimme a break ... (though if someone thought "topology" was better than "analysis," I wouldn't mind))
A metric on a set
is a function
which obeys the following three properties:
- Symmetry:
for all points
.
- Positivity:
for all
and
if and only if
.
- The triangle inequality:
for all
.
Together, the set and the metric
form a metric space.
Common metrics
- For
, the Euclidean metric
is the conventional distance function.
- For any set
, the discrete metric
and
otherwise.
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