Hmm. Try setting extendInt="yes" in the call to uniroot. You should also look at the help page for uniroot. help(uniroot) May give you a clue. It's difficult for me to debug code on my iphone. Well, more difficult than usual.

Best,

Simon.

Sent from my iPhone

On 30 Jun 2014, at 8:53 pm, "Mark Christjani" <m_christjani@gmx.de<mailto:m_christjani@gmx.de>> wrote:

Thank you, Simon, for your input.

Data import works fine now, but the final equation still won`t work.

Console reads now:

> setwd("c:/Mark")
>
> table <- read.table("r-TCO-Scene-Kontrolle.csv", header=TRUE, sep=";")
>
> table
    x  lx  mx
1   1 1.0 0.0
2   2 1.0 0.0
3   3 1.0 0.0
4   4 1.0 0.0
5   5 1.0 0.0
6   6 1.0 0.0
7   7 1.0 0.0
8   8 1.0 0.0
9   9 1.0 0.0
10 10 1.0 0.0
11 11 0.2 3.5
>
> x <- c(table$x)
> L <- c(table$lx)
> m <- c(table$mx)
> r.range<- c(0, 5)
>
> eulerlotka <- function(r) sum(L * m * exp(-r * x)) - 1
> res <- uniroot(f = eulerlotka, interval = r.range, tol = 1e-8)
Error in uniroot(f = eulerlotka, interval = r.range, tol = 1e-08) :
  f() values at end points not of opposite sign
>
> res$root
Error: object 'res' not found

Any idea on this "Error in uniroot(f = eulerlotka, interval = r.range, tol = 1e-08) :
  f() values at end points not of opposite sign"-matter?

Kind regards,
Mark



Gesendet: Montag, 30. Juni 2014 um 12:41 Uhr
Von: "Simon Blomberg" <s.blomberg1@uq.edu.au<mailto:s.blomberg1@uq.edu.au>>
An: "Mark Christjani" <m_christjani@gmx.de<mailto:m_christjani@gmx.de>>
Cc: "r-help@r-project.org<mailto:r-help@r-project.org>" <r-help@r-project.org<mailto:r-help@r-project.org>>
Betreff: Re: [R] Population growthrate with Euler-Lotka
Your script is failing at the first hurdle because you data are not being imported properly. You should include

header=TRUE. sep=";"

In the call to read.table.

Cheers.

Simon.

Sent from my iPhone

Sent from my iPhone
> On 30 Jun 2014, at 7:10 pm, "Mark Christjani" <m_christjani@gmx.de<mailto:m_christjani@gmx.de>> wrote:
>
>
> Hi everybody,
>
> I`m Mark and I do my PhD in biology. I try using R to calculate a population
> growth rate of animals grown on different types of food. Our workgroup has a
> R-skript to do so, but sadly nobody, who knows how this works. I`ve never
> used R before, but got some stuff figured out myself. The skript goes:
>
> setwd("c:/Mark")
> table <- read.table("r-TCO-Scene-Kontrolle.csv")
> table
> x <- c(table$x)
> L <- c(table$lx)
> m <- c(table$mx)
> r.range<- c(0, 5)
> eulerlotka <- function(r) sum(L * m * exp(-r * x)) - 1
> res <- uniroot(f = eulerlotka, interval = r.range, tol = 1e-8)
> res$root
>
> I understood that the first 3 lines are simply to load my data and show it
> in the workspace console. The next 4 lines define variables of my .csv table
> for R. Thus far, everything works fine. Now comes the Euler-Lotka equation,
> but somehow, this does not seem to work out as supposed. I tried to find a
> solution on the internet, but I think this formula is somewhat special so I
> could not find a suitible solution for my special problem. The console says:
>
>
>> setwd("c:/Mark")
>>
>> table <- read.table("r-TCO-Scene-Kontrolle.csv")
>>
>> table
> V1
> 1 x;lx;mx
> 2 1;1;0
> 3 2;1;0
> 4 3;1;0
> 5 4;1;0
> 6 5;1;0
> 7 6;1;0
> 8 7;1;0
> 9 8;1;0
> 10 9;1;0
> 11 10;1;0
> 12 11;0.2;3.5
>>
>> x <- c(table$x)
>> L <- c(table$lx)
>> m <- c(table$mx)
>> r.range<- c(0, 5)
>>
>> eulerlotka <- function(r) sum(L * m * exp(-r * x)) - 1
>> res <- uniroot(f = eulerlotka, interval = r.range, tol = 1e-8)
> Error in uniroot(f = eulerlotka, interval = r.range, tol = 1e-08) :
> f() values at end points not of opposite sign
>>
>> res$root
>
> Does anybody have an idea how to get this running?
>
> Thanks in advance
>
> Kind regards
> Mark
> ______________________________________________
> R-help@r-project.org<mailto:R-help@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.

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