[R] system solver in R

[J C Nash]

A bit pedestrian, but you might try

pf <- function(x){5/((1+x)^1) + 5/((1+x)^2) + 5/((1+x)^3) + 105/((1+x)^4) -105}
uniroot(pf,c(-10,10))
curve(pf, c(-10,10))
require(pracma)
tryn <- newton(pf, 0)
tryn
pf(0)
pf(0.03634399)
yc <- c(-105, 5,5,5,105)
rooty <- polyroot(yc)
rooty
rootx <- 1/rooty - 1
rootx

There are lots of rootfinders, and the histoRicalg project (https://gitlab.com/nashjc/histoRicalg)
that is supported by the R Consortium to look into older codes has quite a bit on rootfinders.

JN

On 2018-11-20 7:09 a.m., Engin Yılmaz wrote:
> 
> 
> Dea(R)
> I try to solve one equation but this program did not give me real roots
> for example
> yacas("Solve( 5/((1+x)^1) + 5/((1+x)^2) + 5/((1+x)^3) + 105/((1+x)^4) -105
> ==0, x)")
> gave me following results
> How can I find real roots?
> 
> expression(list(x == complex_cartesian((1/42 - ((1/63 -
> ((root(7339451281/3087580356,
>     2) - 4535/71442)^(1/3) - (4535/71442 + root(7339451281/3087580356,
>     2))^(1/3)))/21 - -2/21)/(4 * root(((root(7339451281/3087580356,
>     2) - 4535/71442)^(1/3) - (4535/71442 + root(7339451281/3087580356,
>     2))^(1/3) - 1/63)^2/4 + 1, 2)))/2 - 1, root(4 *
> (((root(7339451281/3087580356,
>     2) - 4535/71442)^(1/3) - (4535/71442 + root(7339451281/3087580356,
>     2))^(1/3) - 1/63)/2 + root(((root(7339451281/3087580356,
>     2) - 4535/71442)^(1/3) - (4535/71442 + root(7339451281/3087580356,
>     2))^(1/3) - 1/63)^2/4 + 1, 2)) - (((1/63 -
> ((root(7339451281/3087580356,
>     2) - 4535/71442)^(1/3) - (4535/71442 + root(7339451281/3087580356,
>     2))^(1/3)))/21 - -2/21)/(4 * root(((root(7339451281/3087580356,
>     2) - 4535/71442)^(1/3) - (4535/71442 + root(7339451281/3087580356,
>     2))^(1/3) - 1/63)^2/4 + 1, 2)) - 1/42)^2, 2)/2),...more
> 
> 
> 
> 
> Engin Yılmaz <ispanyolcom using gmail.com>, 20 Kas 2018 Sal, 12:53 tarihinde şunu
> yazdı:
> 
>> Thanks a lot!
>>
>> Berend Hasselman <bhh using xs4all.nl>, 20 Kas 2018 Sal, 12:02 tarihinde şunu
>> yazdı:
>>
>>>
>>>
>>> R package Ryacas may be what you want.
>>>
>>> Berend
>>>
>>>
>>>> On 20 Nov 2018, at 09:42, Engin Yılmaz <ispanyolcom using gmail.com> wrote:
>>>>
>>>> Dea(R)
>>>>
>>>> Do you know any system solver in R ?
>>>>
>>>> For example, in matlab, is very easy
>>>>
>>>> syms a b c x eqn = a*x^2 + b*x + c == 0; sol = solve(eqn)
>>>>
>>>> How can I  find this type code in R (or directly solver)?
>>>>
>>>> *Since(R)ely*
>>>> Engin YILMAZ
>>>>
>>>>       [[alternative HTML version deleted]]
>>>>
>>>> ______________________________________________
>>>> R-help using 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.
>>>
>>>
>>
>> --
>> *Saygılarımla*
>> Engin YILMAZ
>>
> 
> 
> -- 
> *Saygılarımla*
> Engin YILMAZ
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help using 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.
>