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Steve Rowe commented on LUCENE-7974: ------------------------------------ bq. I'm wondering whether the use of getMinDelta could be replaced with Math.nextUp/Math.nextDown? These do different things, and I'm not sure how to express one in terms of the other. Suggestions welcome :). {{getMinDelta}} calculates a fudge factor from the distance exponent reduced by (at most) 23, the number of bits in a float mantissa. This is necessary when the result of subtracting/adding the distance in a single dimension has an exponent that differs significantly from the distance value. Without this fudge factor (i.e. only subtracting/adding the distance), cells and values can be inappropriately judged as outside the search radius. By contrast, {{Math.nextUp}}/{{Math.nextDown}} produce adjacent values (i.e. the equivalent of incrementing/decrementing the mantissa value by one). > Add N-dimensional FloatPoint K-nearest-neighbor implementation > -------------------------------------------------------------- > > Key: LUCENE-7974 > URL: https://issues.apache.org/jira/browse/LUCENE-7974 > Project: Lucene - Core > Issue Type: New Feature > Components: modules/sandbox > Reporter: Steve Rowe > Assignee: Steve Rowe > Priority: Minor > Attachments: LUCENE-7974.patch > > > From LUCENE-7069: > {quote} > KD trees (used by Lucene's new dimensional points) excel at finding "nearest > neighbors" to a given query point ... I think we should add this to Lucene's > sandbox > [...] > It could also be generalized to more than 2 dimensions, but for now I'm > making the class package private in sandbox for just the geo2d (lat/lon) use > case. > {quote} > This issue is to generalize {{LatLonPoint.nearest()}} to more than 2 > dimensions. -- This message was sent by Atlassian JIRA (v6.4.14#64029) --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@lucene.apache.org For additional commands, e-mail: dev-h...@lucene.apache.org