[R] Odp: ^ operator

[Alain Guillet]

Hi,

You forgot to put the parenthesis in the way Petr told you : 
(-6.108576e-05)^(1/3)  and the result is NaN. What do you want to preserve?


Alain




carol white wrote:
> but with complex, I get complex numbers for the first and last elements:
>
>   
>> (as.complex(tmp))^(1/3)
>>     
> [1] 0.01969170+0.03410703i 0.03478442+0.00000000i 0.03285672+0.00000000i
> [4] 0.08950802+0.00000000i 0.05848363+0.10129661i
>
> whereas for the first element, we get the followings.
>
> Moreover, 
>   
>> -6.108576e-05^(1/3)
>>  [1] -0.03938341
>>     
> and
>   
>> -(6.108576e-05^(1/3))
>>     
> [1] -0.03938341
> and
>  -((6.108576e-05)^(1/3))
> [1] -0.03938341
>
> give the same results.
>
> so using () doesn't preserve any thing
>
> --- On Mon, 11/16/09, Petr PIKAL <petr.pikal at precheza.cz> wrote:
>
>   
>> From: Petr PIKAL <petr.pikal at precheza.cz>
>> Subject: Odp: [R] ^ operator
>> To: "carol white" <wht_crl at yahoo.com>
>> Cc: r-help at stat.math.ethz.ch
>> Date: Monday, November 16, 2009, 3:40 AM
>> Hi
>>
>> AFAIK, this is issue of the preference of operators. 
>>
>> r-help-bounces at r-project.org
>> napsal dne 16.11.2009 11:24:59:
>>
>>     
>>> Hi,
>>> I want to apply ^ operator to a vector but it is
>>>       
>> applied to some of the 
>>     
>>> elements correctly and to some others, it generates
>>>       
>> NaN. Why is it not 
>> able to
>>     
>>> calculate -6.108576e-05^(1/3) even though it exists?
>>>
>>>
>>>   tmp
>>> [1] -6.108576e-05  4.208762e-05 
>>>       
>> 3.547092e-05  7.171101e-04 
>> -1.600269e-03
>>     
>>>> tmp^(1/3)
>>>>         
>>> [1]        NaN 0.03478442
>>>       
>> 0.03285672 0.08950802        NaN
>>
>> This computes (-a)^(1/3) which is not possible in real
>> numbers. You have 
>> to use as.complex(tmp)^(1/3) to get a result.
>>
>>     
>>>> -6.108576e-05^(1/3)
>>>>         
>>> [1] -0.03938341
>>>       
>> this is actually
>> -(6.108576e-05^(1/3))
>>
>> Regards
>> Petr
>>
>>
>>     
>>> ______________________________________________
>>> R-help at r-project.org
>>>       
>> mailing list
>>     
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide 
>>>       
>> http://www.R-project.org/posting-guide.html
>>     
>>> and provide commented, minimal, self-contained,
>>>       
>> reproducible code.
>>
>>
>>     
>
>
>
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
>   

-- 
Alain Guillet
Statistician and Computer Scientist

SMCS - Institut de statistique - Université catholique de Louvain
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