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What is epsilon and why do we need it in GIS operations?

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This question needs a context: "epsilon" is merely the name of a Greek letter. It is not a conventional or widely recognized term for a procedure or concept in GIS. –  whuber Nov 24 '10 at 16:35

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up vote 5 down vote accepted

I've seen this used in the context of clustering. If two points are less than or equal to epsilon distance of each other, they are considered to be in the same location.

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Epsilon equivalence testing is also frequently used in geometric algebra operations that use floating point math. As Kirk said, if two points are less than or equal to epsilon in all dimensions, they are considered equivalent.

Wikipedia provides some good background on epsilon and limit testing.

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That Wikipedia reference does not seem pertinent to your answer. –  whuber Nov 24 '10 at 16:34
    
Better Wikipedia link: machine epsilon –  Mike T Mar 12 '12 at 3:27

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