distance

[[concept]]

A metric or distance is a function d:M×MR that satisfies

  1. d(x,x)=0
  2. d(x,y)>0xy
  3. d(x,y)=d(y,x)
  4. d(x,z)d(x,y)+d(y,z)

This is part of the definition of a metric space.

functional analysis

Metric

If X is a set then d:X×X[0,) is a metric if

  1. (identifiability) d(x,y)=0x=y
  2. (symmetry) x,yX,d(x,y)=d(y,x)
  3. (triangle inequality) x,y,zX,d(x,y)d(x,z)+d(z,y)

Reference

see also

Mentions

Mentions

Created 2025-03-24 Last Modified 2025-05-27