[R] How to solve following equation?

RON70 ron_michael70 at yahoo.com
Wed Dec 3 18:32:28 CET 2008

```Thanks for this reply, However I am interested to know why I need to modify
my function to a=1?

Regards,

Gabor Grothendieck wrote:
>
> Assume a = 1.  If not set b = b/a, etc.
> Now use (1) uniroot
>
>> f <- function(x) b + c/(1+x) + d/(1+x)^2 - 1 - x
>> uniroot(f, 0:1)
> \$root
> [1] 0.8392679
>
> \$f.root
> [1] 3.049818e-05
>
> \$iter
> [1] 3
>
> \$estim.prec
> [1] 6.103516e-05
>
> or multiply through by 1+x
> and subtract 1 from both sides giving
> x = b + c/(1+x) + d/(1+x)^2 - 1
> and iterate that.
>
>> a <- b <- c <- d <- 1
>> x <- 0
>> for(i in 1:25) {
> + x <- b + c/(1+x) + d/(1+x)^2 - 1
> + print(x)
> + }
> [1] 2
> [1] 0.4444444
> [1] 1.171598
> [1] 0.6725419
> [1] 0.9553676
> [1] 0.7729558
> [1] 0.8821595
> [1] 0.8135892
> [1] 0.8554268
> [1] 0.829437
> [1] 0.8454056
> [1] 0.835527
> [1] 0.8416126
> [1] 0.837854
> [1] 0.8401717
> [1] 0.838741
> [1] 0.8396236
> [1] 0.839079
> [1] 0.839415
> [1] 0.8392076
> [1] 0.8393356
> [1] 0.8392566
> [1] 0.8393053
> [1] 0.8392753
> [1] 0.8392938
>
> On Mon, Dec 1, 2008 at 9:47 PM, RON70 <ron_michael70 at yahoo.com> wrote:
>>
>> I need to solve a equation like this :
>>
>> a = b/(1+x) + c/(1+x)^2 + d/(1+x)^3
>>
>> where a,b,c,d are known constant. Is there any R-way to do that?
>>
>> --
>> View this message in context:
>> http://www.nabble.com/How-to-solve-following-equation--tp20785063p20785063.html
>> Sent from the R help mailing list archive at Nabble.com.
>>
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>> and provide commented, minimal, self-contained, reproducible code.
>>
>
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