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40 lines
1 KiB
Text
40 lines
1 KiB
Text
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Statistical aggregate functions for PostgreSQL.
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This module provides some aggregate functions for statistical
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mathematics. A new datatype holding two double precision
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floating point values is required by them.
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The aggregates are:
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average(float8) average value computed by
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n
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___
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_ 1 \
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x = --- > x
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n /__ i
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i=1
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variance(float8 variance computed by
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n
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___
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2 1 \ _ 2
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s = --- > (x - x)
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n-1 /__ i
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i=1
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stddev(float8) standard deviation computed by
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_____
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/ 2
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s = / s
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\/
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--
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Jan Wieck <JanWieck@Yahoo.com>
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