Please do not forget to CC the list to increase your chances of getting
help. --JIV
On Wed, Apr 10, 2013 at 9:31 PM, catalin roibu
<catalinroibu@gmail.com>wrote:
> Hello!
> I try to compute the double exponential function this code:
> f<-function(cls,a,b,c,d)a*exp(cls*b)+c*exp(cls*d)
>
>
n2<-nls(proc~f(cls,a,b,c,d),data=bline,start=list(a=600,b=-.1,c=4,d=-.1),trace=TRUE)
> proc~f(cls,a,b,c,d)
>
> but don't work!
>
> Thanks!
>
>
>
> On 10 April 2013 12:47, catalin roibu <catalinroibu@gmail.com> wrote:
>
>> Hello!
>> I try to nls and I compute a simple exponential equation, but the
problem
>> in nls is to anticipate the regression coefficients.
>>
>>
>> On 10 April 2013 12:19, Jorge I Velez <jorgeivanvelez@gmail.com>
wrote:
>>
>>> Dear Catalin,
>>>
>>> You can look at ?nls.
>>>
>>> Alternatively, you could also consider a linear model as follows,
where
>>> "d" is your data:
>>>
>>> # plot your data
>>> with(d, plot(cls, proc, las = 1))
>>>
>>> # linear model
>>> fit <- lm(proc ~ I(1/cls) + I((1/cls)^2), data = d)
>>> summary(fit)
>>>
>>> # plotting
>>> with(d, plot(cls, proc, las = 1))
>>> grid <- seq(min(d$cls), max(d$cls), length = 1000)
>>> points(grid, predict(fit, data.frame(cls = grid)), type =
"l", col = 2)
>>>
>>> HTH,
>>> Jorge.-
>>>
>>>
>>>
>>>
>>> On Wed, Apr 10, 2013 at 7:01 PM, catalin roibu
<catalinroibu@gmail.com>wrote:
>>>
>>>> Hello all!
>>>>
>>>> I have a problem with a double exponential equation.
>>>> this are my data's>
>>>> structure(list(proc = c(1870.52067384719, 766.789388745793,
>>>> 358.701545859122,
>>>> 237.113777545511, 43.2726259059654, 148.985133316262,
92.6242882655781,
>>>> 88.4521557193262, 56.6404686159112, 27.0374477259404,
34.3347291080268,
>>>> 18.3226992991316, 15.2196612445747, 5.31600719692165,
16.7015717397302,
>>>> 16.3923389973684, 24.2702542054496, 21.247247993673,
18.3070717608672,
>>>> 2.8811892177331, 3.18018869564679, 8.74204132937479,
7.11596966047229
>>>> ), cls = c(0.25, 0.5, 0.75, 1, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5,
>>>> 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10)), .Names =
c("proc",
>>>> "cls"), row.names = c("0.25",
"0.5", "0.75", "1", "11",
"1.5",
>>>> "2", "2.5", "3", "3.5",
"4", "4.5", "5", "5.5", "6",
"6.5", "7",
>>>> "7.5", "8", "8.5", "9",
"9.5", "10"), class = "data.frame")
>>>> I want to compute a double exponential equation like this:
>>>> proc=a*exp(b*class)+c*exp(d*class)
>>>> or
>>>> proc=a*exp(b*class)+c*class
>>>> or a power, logarithmic equation.
>>>> Is there a possibility to calculate R squared for each model?
>>>>
>>>> Thank you!
>>>>
>>>> --
>>>> ---
>>>> Catalin-Constantin ROIBU
>>>> Lecturer PhD, Forestry engineer
>>>> Forestry Faculty of Suceava
>>>> Str. Universitatii no. 13, Suceava, 720229, Romania
>>>> office phone +4 0230 52 29 78, ext. 531
>>>> mobile phone +4 0745 53 18 01
>>>> +4 0766 71 76 58
>>>> FAX: +4 0230 52 16 64
>>>> silvic.usv.ro
>>>>
>>>> [[alternative HTML version deleted]]
>>>>
>>>> ______________________________________________
>>>> 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.
>>>>
>>>
>>>
>>
>>
>> --
>> ---
>> Catalin-Constantin ROIBU
>> Lecturer PhD, Forestry engineer
>> Forestry Faculty of Suceava
>> Str. Universitatii no. 13, Suceava, 720229, Romania
>> office phone +4 0230 52 29 78, ext. 531
>> mobile phone +4 0745 53 18 01
>> +4 0766 71 76 58
>> FAX: +4 0230 52 16 64
>> silvic.usv.ro
>>
>
>
>
> --
> ---
> Catalin-Constantin ROIBU
> Lecturer PhD, Forestry engineer
> Forestry Faculty of Suceava
> Str. Universitatii no. 13, Suceava, 720229, Romania
> office phone +4 0230 52 29 78, ext. 531
> mobile phone +4 0745 53 18 01
> +4 0766 71 76 58
> FAX: +4 0230 52 16 64
> silvic.usv.ro
>
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