ST_MaxDistance
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## Name

ST_MaxDistance — Returns the 2D largest distance between two geometries in projected units.

## Synopsis

`float ST_MaxDistance(`geometry g1, geometry g2`)`;

## Description

Returns the 2-dimensional maximum distance between two geometries, in projected units. The maximum distance always occurs between two vertices. This is the length of the line returned by ST_LongestLine.

If g1 and g2 are the same geometry, returns the distance between the two vertices farthest apart in that geometry.

Availability: 1.5.0

## Examples

Maximum distance between a point and lines.

    SELECT ST_MaxDistance('POINT(0 0)'::geometry, 'LINESTRING ( 2 0, 0 2 )'::geometry);
    -----------------
     2

    SELECT ST_MaxDistance('POINT(0 0)'::geometry, 'LINESTRING ( 2 2, 2 2 )'::geometry);
    ------------------
     2.82842712474619

Maximum distance between vertices of a single geometry.

    SELECT ST_MaxDistance('POLYGON ((10 10, 10 0, 0 0, 10 10))'::geometry,
                          'POLYGON ((10 10, 10 0, 0 0, 10 10))'::geometry);
    ------------------
     14.142135623730951

## See Also

ST_Distance, ST_LongestLine, ST_DFullyWithin

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