asked on

(100 pts)Geometric to Harmonic mean

Hello everyone.
I have recently been computing the geometric mean of a column in out SQL Server 2000 DB using the following script:
exp(avg(log(Column_name)))

this has worked great, however I need to change this to the harmonic mean. Anyone have any ideas on the simplest way to do this.
A simple example of the harmonic mean:
If you want the harmonic mean of 10 and 20, you first
take 1/10 and 1/20, find their average, which is 3/40, and then take
the reciprocal of that, 40/3.

In algebra, the harmonic mean h of two numbers a and b is

1 / ( (1/a + 1/b) / 2),

or in other words

1/m = 1/2 (1/a + 1/b).

Thanks for any help!

I am also awarding the poitns from this question. (100 pts total)
https://www.experts-exchange.com/questions/20694999/Geometric-Mean-Function.html

ASKER CERTIFIED SOLUTION

graye

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mohamadalikley

I First build at atble with the following discription
CREATE TABLE [test] (
[a] [float] NOT NULL
) ON [PRIMARY]
GO

then ask it the following question :
declare @c float ;
declare @d int ;

Select @c = sum(1/a) From test ;
Select @d = count(*) FROM test ;
print @d *(1/@c)

and it work quit good .

hope it will be usefull for you.

gigglick

ASKER

Hi guys,
Thank you both for your posts. I am sure both should work, however, I have already found working solution (very similar to yours graye) with some help.
Here is the xript in case any searchers com across this question: 1.0/(sum(1/column_name)/count(column))

Hope you guys are ok with me splitting the points between the both of you.

Thanks again!

gigglick

ASKER

You"ll need to go to :
https://www.experts-exchange.com/questions/20694999/Geometric-Mean-Function.html
and post something for me to split the remaining points.
Thanks again!