The BIASDISTCARTESIAN
field operator works in a similar way to the BIAS
field operator. It allows you to bias the score of results at query time according to the proximity of the specified field to a particular location, specified using Cartesian coordinates.
Specify BIASDISTCARTESIAN
in the format:
FieldText=BIASDISTCARTESIAN{coordX,coordY,range,percentage}:X:Y
where:
coordX

is the X coordinate. 
coordY

is the Y coordinate. 
range

is the distance in kilometers from the coordinates. If the fields contain the coordinates of a location that is within this distance of the coordinates, the results weight increases or decreases according to the specified percentage. 
percentage

is a percentage in the range –100 to 100. If the value of the field is within the specified range, the score of the result increases or decreases according to how close the value is to the optimum. 
X

is the document field that contains the X coordinate. 
Y

is the document field that contains the Y coordinate. 
You must specify two fields in the order X:Y. The fields must be of NumericType
.
For example:
FieldText=BIASDISTCARTESIAN{10,11,5,7}:X:Y
In this example, all documents whose (X/Y) position is within a distance of 5 units of the point (10,11) are given a relevance boost. The maximum boost of 7 percent is given to documents at the specified point. The boost decreases linearly down to zero boost at 5 units.
