From: <jessica.gervais_at_tudor.lu>

Date: Wed 27 Sep 2006 - 16:34:33 GMT

R-help@stat.math.ethz.ch 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. Received on Thu Sep 28 02:47:41 2006

Date: Wed 27 Sep 2006 - 16:34:33 GMT

Hi,

I am trying to fit experimental points by exponemtial curve

my data are stored into a matrix data

if I plot ln y = ax+b , everything goes fine

xyplot(log(data[,3])~data[,2]|data[,1],panel=function(x,y){panel.xyplot(x,y)+panel.abline(coef(lm(y~x)))}) and I get perfect linear regression of my points

...But I would prefer to plot the exponential curves (y=exp ( a*x + b )).. I tried the following formula :

*>
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xyplot(data[,3]~data[,2]|data[,1],panel=function(x,y){panel.xyplot(x,y)+panel.curve(coef(lm(log(y)~x))[1])})

and I get :

Error in model.frame(formula, rownames, variables, varnames, extras,
extranames, :

variable lengths differ (found for 'x')

... I don't really now what goes wrong and how to correct that Maybe I am wrong in the use of the pannel.curve function ....

Do anyone know something about that ?

Thanks by advance

Jessica Gervais

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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. Received on Thu Sep 28 02:47:41 2006

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