To implement window aggregates of percentile into SciDB as a plugin user-defined-operator
SciDB Version: 13.12

Optimized with incremental computation, performance greatly improved comparing with naive methods.

Check paper : Incremental window aggregates over array database
Link : http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=7004230&url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel7%2F6973861%2F7004197%2F07004230.pdf%3Farnumber%3D7004230

=================== Usages: copy libpercentile.so into the scidb plugin dir,
run the following command within 'iquery' client of SciDB
AFL% load_library('percentile');

Then percentile can be used.

percentile(Array_name, dim1_low, dim1_high, [dim2_low, dim2_high, ...], attr_name, percentile_percentage, [Method]);
As a window aggregate, the pairs of dim_low, dim_high are used to define the window size, just the same as 'window' operator in SciDB, can be refered in SciDB Userguide.
attr_name refers to the attribute to be computed over.
[Method] refers to the method used for the query.
--'qsort' refers to quicksort method
--'BST' refers to incremental computation.

==================== To Make:
Need to modify the Makefile, set the SciDB-Source Directory with correct location in your machine.
A few libraries needed to compile, same ones as building SciDB from Source Code.