You actually specify the following call to lm:

y <- sin(x)/x

lm(z ~ y - 1)

to make sure that the intercept is not estimated.

Ravi.

----- Original Message -----

From: Ravi Varadhan <rvaradha@jhsph.edu>

Date: Monday, February 2, 2004 2:46 pm

Subject: Re: [R] Robust nonlinear regression - sin(x)/x?

You reall have only one parameter in your model, c = a/b. You

can't

identify both a and b from your model, therefore, you should fit

the

linear model: lm(z ~ c* sin(x)/x)

Ravi.

----- Original Message -----

From: cstrato <cstrato@aon.at>

Date: Monday, February 2, 2004 2:28 pm

Subject: [R] Robust nonlinear regression - sin(x)/x?

R-help at stat.math.ethz.ch mailing list

https://www.stat.math.ethz.ch/mailman/listinfo/r-help

PLEASE do read the posting guide! http://www.R-

project.org/posting-

guide.html______________________________________________

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guide.html

can't

identify both a and b from your model, therefore, you should fit

the

linear model: lm(z ~ c* sin(x)/x)

Ravi.

----- Original Message -----

From: cstrato <cstrato@aon.at>

Date: Monday, February 2, 2004 2:28 pm

Subject: [R] Robust nonlinear regression - sin(x)/x?

Dear all

Since I did not receive any answer to my general question (?),

let me ask a concrete question:

How can I fit the simple function y = a*sin(x)/b*x?

This is the code that I tried, but nls gives an error:

x <- seq(1,10,0.1)

y <- sin(x)/x

plot(x,y)

z <- jitter(y,amount=0.1)

plot(x,z)

df <- as.data.frame(cbind(x,z))

nf <- nls(z ~ a*sin(x)/b*x, data=df,

start=list(a=0.8,b=0.9), trace = TRUE)

I have followed the Puromycin sample which works fine:

Pur.wt <- nls(rate ~ (Vm * conc)/(K + conc), data = Treated,

start = list(Vm = 200, K = 0.1), trace = TRUE)

Do I make some mistake or is it not possible to fit sin(x)/x?

Thank you in advance

Best regards

Christian

_._._._._._._._._._._._._._._._

C.h.i.s.t.i.a.n S.t.r.a.t.o.w.a

V.i.e.n.n.a A.u.s.t.r.i.a

_._._._._._._._._._._._._._._._

cstrato wrote:

rsch.com/admodel/cc1.html> > but no mention of R/SSince I did not receive any answer to my general question (?),

let me ask a concrete question:

How can I fit the simple function y = a*sin(x)/b*x?

This is the code that I tried, but nls gives an error:

x <- seq(1,10,0.1)

y <- sin(x)/x

plot(x,y)

z <- jitter(y,amount=0.1)

plot(x,z)

df <- as.data.frame(cbind(x,z))

nf <- nls(z ~ a*sin(x)/b*x, data=df,

start=list(a=0.8,b=0.9), trace = TRUE)

I have followed the Puromycin sample which works fine:

Pur.wt <- nls(rate ~ (Vm * conc)/(K + conc), data = Treated,

start = list(Vm = 200, K = 0.1), trace = TRUE)

Do I make some mistake or is it not possible to fit sin(x)/x?

Thank you in advance

Best regards

Christian

_._._._._._._._._._._._._._._._

C.h.i.s.t.i.a.n S.t.r.a.t.o.w.a

V.i.e.n.n.a A.u.s.t.r.i.a

_._._._._._._._._._._._._._._._

cstrato wrote:

Dear R experts

This is a general question:

Does R have functions for nonlinear robust regression,

analogous to e.g. LTS?

Searching google I have found

1, an abstract to generalize LTS for nonlinear regression

models, see: http://smealsearch.psu.edu/1509.html

2, an AD-model builder, see: http://otter-

This is a general question:

Does R have functions for nonlinear robust regression,

analogous to e.g. LTS?

Searching google I have found

1, an abstract to generalize LTS for nonlinear regression

models, see: http://smealsearch.psu.edu/1509.html

2, an AD-model builder, see: http://otter-

Thank you in advance

Best regards

Christian

_._._._._._._._._._._._._._._._

C.h.i.s.t.i.a.n S.t.r.a.t.o.w.a

V.i.e.n.n.a A.u.s.t.r.i.a

_._._._._._._._._._._._._._._._

______________________________________________

R-help at stat.math.ethz.ch mailing list

https://www.stat.math.ethz.ch/mailman/listinfo/r-help

PLEASE do read the posting guide!

http://www.R-project.org/posting-guide.html

______________________________________________Best regards

Christian

_._._._._._._._._._._._._._._._

C.h.i.s.t.i.a.n S.t.r.a.t.o.w.a

V.i.e.n.n.a A.u.s.t.r.i.a

_._._._._._._._._._._._._._._._

______________________________________________

R-help at stat.math.ethz.ch mailing list

https://www.stat.math.ethz.ch/mailman/listinfo/r-help

PLEASE do read the posting guide!

http://www.R-project.org/posting-guide.html

R-help at stat.math.ethz.ch mailing list

https://www.stat.math.ethz.ch/mailman/listinfo/r-help

PLEASE do read the posting guide! http://www.R-

project.org/posting-

guide.html

R-help at stat.math.ethz.ch mailing list

https://www.stat.math.ethz.ch/mailman/listinfo/r-help

PLEASE do read the posting guide! http://www.R-project.org/posting-

guide.html