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postgres/contrib/statmath
History
Jan Wieck 31a020f6eb
Added CVS header 		26 years ago
..
Makefile New contrib module for statistical mathematics 26 years ago
README.statmath New contrib module for statistical mathematics 26 years ago
statmath.c Added CVS header 26 years ago
statmath.sql.in New contrib module for statistical mathematics 26 years ago

README.statmath 

Statistical aggregate functions for PostgreSQL.

This module provides some aggregate functions for statistical 
mathematics. A new datatype holding two double precision 
floating point values is required by them. 

The aggregates are:

average(float8)         average value computed by

                                   n
                                  ___
                        _    1    \
                        x = ---    >  x
                             n    /__  i
                                  i=1


variance(float8         variance computed by

                                    n
                                   ___
                         2    1    \         _ 2
                        s  = ---    >  (x  - x) 
                             n-1   /__   i
                                   i=1



stddev(float8)          standard deviation computed by

                                 _____
                                /  2 
                        s =    /  s
                             \/


-- 
Jan Wieck <JanWieck@Yahoo.com>