Dear duncan,
Sorry to bother you with such a silly mistake I
didn,t notice it!
Sent: Tuesday, March 19, 2019 6:01 PM
To: akshay kulkarni; R help Mailing list
Subject: Re: [R] Fw: problem with nlsLM function
On 19/03/2019 8:26 a.m., akshay kulkarni wrote:
>
> dear members,
> also,I can provide HM1,HM2 and HM3 if needed
>
>
> From: R-help on behalf of akshay kulkarni
>
> Sent: Tuesday, March 19, 2019 5:43 PM
> To: R help Mailing list
> Subject: [R] problem with nlsLM function
>
> dear members,
> I am getting the "singular gradient error" when I use
> nls for a function of two variables:
>> formulaDH5
> HM1 ~ (a + (b * ((HM2 + 0.3)^(1/2 + (A * sin(w * HM3 + a) +
> C)
>
> HM1 is the response variable, and HM2 and HM3 are predictors.
>
> The problem is I get the same error even when I use nlsLM(in the minpack.lm
> package):
>
>> nonlin_modDH5 <- nlsLM(formulaDH5, start = list(a = 0.43143, b = 2,A =
>> 0.09,w = 0.8,a = 0.01,C = 0.94))
You have "a" twice in your start list. That's bound to cause trouble...
Duncan Murdoch
> Error in nlsModel(formula, mf, start, wts) :
>singular gradient matrix at initial parameter estimates
>> nonlin_modDH5 <- nlsLM(formulaDH5, start = list(a = 1, b = 2,A = 0.09,w =
>> 0.8,a = 0.01,C = 0.94))
> Error in nlsModel(formula, mf, start, wts) :
>singular gradient matrix at initial parameter estimates
>> nonlin_modDH5 <- nlsLM(formulaDH5, start = list(a = 1, b = 2,A = 0.09,w =
>> 0.8,a = 0.01,C = 2))
> Error in nlsModel(formula, mf, start, wts) :
>singular gradient matrix at initial parameter estimates
>
> I came to know that nlsLM converges when nls throws a singular gradient
> error. What is happening above? Can the problem get solved if I use nls.lm
> function(in the minpack.lm package) instead?
>
> very many thanks for your time and effort
> yours sincerely,
> AKSHAY M KULKARNI
>
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>
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> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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