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Re: Bug in geomean()


From: Sergei Steshenko
Subject: Re: Bug in geomean()
Date: Mon, 1 Oct 2012 09:19:09 -0700 (PDT)




----- Original Message -----
> From: kyfsympsn <address@hidden>
> To: address@hidden
> Cc: 
> Sent: Monday, October 1, 2012 5:25 PM
> Subject: Re: Bug in geomean()
> 
>T hanks Jordi,
> 
> 
>>  I think it's a good habit to inspect the source code if you want to
>>  know how something is being done.
> 
> Yeah, sorry... making the switch from Matlab, so I'm not yet in the habit of
> "looking under the hood" at the source code :-)
> 
> 
>>  Can you provide a patch? It should take into account the cases of
>>  complex, negative, or zero entries. 
> 
> the basic fix is to change that line 116 from:
>    y = prod (x, dim) .^ (1/n);
> to:
>    y = exp (sum(log(x), dim) ./n);
> 
> --zero entries in x will correctly return 0
> 
[snip]
> 
> Many thanks
> Keith


According to how I was taught math and computing taking log(x) for x == 0 is 
illegal even if it in the end produces the expected result.


Regards,
 Sergei.



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