R help - Nov 2016 - Partial Fraction Decomposition

Hello Folks,

As a neophyte R user I frequently have questions, and I?m sorry to bother
experienced users with what may appear to be trivial questions to which I should
be able to find answers without help.  I?ve searched everywhere I know to look,
and can?t find any reference to this question.  Perhaps I just haven't
guessed a correct keyword for my searches.  I apologize in advance.

Given a rational expression P/Q with P and Q being polynomials that are prime in
relation to each other, and with Q factored, is there an R function or package
that will return the partial fraction decomposition of P/Q?

For example:
Given (3x^3+x^2-8x+6)/(x^2)(x-1)^2
Return 4/x + 6/x^2 ? 1/(x-1) + 2/(x-1)^2

Thank you, Tom

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I am not aware that R really does symbolic manipulation in the way which you
want, but I would have thought that this process would make a very pretty little
problem to solve for you yourself, in that you could write a programme to
analyse the original expression as a string of characters, whose particular
nature means that you have to make certain choices.  Start with a simple
example, say (x^2 + x +1)/(x+1) (i haven't actually worked this out) and
gradually work up

Nick
> 
>     On 26 November 2016 at 23:18 Tom Mosca <tom at vims.edu> wrote:
> 
> 
>     Hello Folks,
> 
>     As a neophyte R user I frequently have questions, and I?m sorry to
bother
> experienced users with what may appear to be trivial questions to which I
> should be able to find answers without help. I?ve searched everywhere I
know
> to look, and can?t find any reference to this question. Perhaps I just
haven't
> guessed a correct keyword for my searches. I apologize in advance.
> 
>     Given a rational expression P/Q with P and Q being polynomials that are
> prime in relation to each other, and with Q factored, is there an R
function
> or package that will return the partial fraction decomposition of P/Q?
> 
>     For example:
>     Given (3x^3+x^2-8x+6)/(x^2)(x-1)^2
>     Return 4/x + 6/x^2 ? 1/(x-1) + 2/(x-1)^2
> 
>     Thank you, Tom
> 
>     [[alternative HTML version deleted]]
> 
>     ______________________________________________
>     R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>     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.
>
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On 27/11/16 22:09, WRAY NICHOLAS wrote:
> I am not aware that R really does symbolic manipulation in the way which
you
> want, but I would have thought that this process would make a very pretty
little
> problem to solve for you yourself, in that you could write a programme to
> analyse the original expression as a string of characters, whose particular
> nature means that you have to make certain choices.  Start with a simple
> example, say (x^2 + x +1)/(x+1) (i haven't actually worked this out)
and
> gradually work up
A quick Google search reveals Ryacas and rSymPy as (at least) two 
packages that do symbolic manipulations.  I have never used either, and 
don't know if they do the partial fraction calculations that the OP 
wanted.  But they'd be worth checking out.

cheers,

Rolf Turner

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