From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thorsten Jolitz <tjolitz@gmail.com>
Subject: Re: Computations on properties
Date: Wed, 09 Oct 2013 14:50:11 +0200
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Thierry Pellé <thierry.pelle@soliavos.fr> writes:

Hi,
>   I'm seeking how to do something like that
>
> Let the following text inserted in an org-mode file
>
> * Mean Calculation
>  :PROPERTIES:
>  :VAL1: 5
>  :VAL2: 10
>  :COEF: 10
>  :END:
>
> I would like to append the result of a computation 
> like RES=(VAL1*COEF+VAL2)/(COEF+1) 
>
> Something like 
> * Mean Calculation
> ...
>   :END:
>
> Mean Calculation=RES (where RES is the value of the result)
>
> I think to do this with a python script but is there a more org-mode/emacs
> method to do it?
>
> Thanks
> Thierry 
>
> PS: I don't want to use org spreadsheet

But that would probably be the appropriate tool. Otherwise you could use
the property API in an elisp program

,------------------------------------------------------
| http://orgmode.org/manual/Using-the-property-API.html
`------------------------------------------------------

to read out the property values. Then do the calculation and finally add
a new property with the result.

-- 
cheers,
Thorsten