[R] Infinite Series
Bert Gunter
bgunter.4567 at gmail.com
Sat Jul 25 01:57:23 CEST 2015
Janh:
It sounds like you really need to go through an R tutorial or two
before posting further, as this is a pretty basic query. Or am I wrong
about this?
An answer: Just use indexing
cumsum(1/seq_len(100)^2)[seq(10, to = 100,by = 10)] ## keeps every 10th
[1] 1.549768 1.596163 1.612150 1.620244 1.625133 1.628406 1.630750
1.632512 1.633884
[10] 1.634984
But beware FAQ 7.31 for long series.
Cheers,
Bert
Bert Gunter
"Data is not information. Information is not knowledge. And knowledge
is certainly not wisdom."
-- Clifford Stoll
On Fri, Jul 24, 2015 at 4:37 PM, Janh Anni <annijanh at gmail.com> wrote:
> Hello Jeff,
>
> Thanks a lot. I tried it and see that it prints out the entire 100 partial
> sums, so I can take the last value as the partial sum for the first 100
> terms. Would there be any way cumsum can print only the nth partial sum,
> i.e. the last value in the array, instead of printing the entire array?
> Thanks again.
>
> Joseph
>
> On Fri, Jul 24, 2015 at 2:02 PM, Jeff Newmiller <jdnewmil at dcn.davis.ca.us>
> wrote:
>
>> Please reply-all so the mailing list stays in the loop.
>>
>> cumsum(1/(1:100)^2)
>>
>> gives you the partial sums up through i=100.
>> ---------------------------------------------------------------------------
>> Jeff Newmiller The ..... ..... Go Live...
>> DCN:<jdnewmil at dcn.davis.ca.us> Basics: ##.#. ##.#. Live
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>> Sent from my phone. Please excuse my brevity.
>>
>> On July 24, 2015 10:30:09 AM PDT, Janh Anni <annijanh at gmail.com> wrote:
>> >Hello Jeff,
>> >
>> >Thank you so much for the suggestion, I searched cumsum as suggested
>> >but
>> >not sure it is what I had in mind. For instance if I had the infinite
>> >series: [image: Inline image 1]
>> >
>> >and want to compute the sum of the, say, first 100 terms, how could I
>> >use
>> >cusum to do that?
>> >
>> >Thanks again,
>> >
>> >Janh
>> >
>> >
>> >On Thu, Jul 23, 2015 at 11:51 PM, Jeff Newmiller
>> ><jdnewmil at dcn.davis.ca.us>
>> >wrote:
>> >
>> >> ?cumsum
>> >>
>>
>> >---------------------------------------------------------------------------
>> >> Jeff Newmiller The ..... ..... Go
>> >Live...
>> >> DCN:<jdnewmil at dcn.davis.ca.us> Basics: ##.#. ##.#. Live
>> >> Go...
>> >> Live: OO#.. Dead: OO#..
>> >Playing
>> >> Research Engineer (Solar/Batteries O.O#. #.O#. with
>> >> /Software/Embedded Controllers) .OO#. .OO#.
>> >rocks...1k
>> >>
>>
>> >---------------------------------------------------------------------------
>> >> Sent from my phone. Please excuse my brevity.
>> >>
>> >> On July 23, 2015 8:23:39 PM PDT, Janh Anni <annijanh at gmail.com>
>> >wrote:
>> >> >Dear All,
>> >> >
>> >> >Does anyone know of any R functions that compute partial sums of
>> >> >series?
>> >> >
>> >> >Thanks in advance!
>> >> >
>> >> >Janh
>> >> >
>> >> > [[alternative HTML version deleted]]
>> >> >
>> >> >______________________________________________
>> >> >R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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>> >> >PLEASE do read the posting guide
>> >> >http://www.R-project.org/posting-guide.html
>> >> >and provide commented, minimal, self-contained, reproducible code.
>> >>
>> >>
>>
>>
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
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