search for: sslogarithm

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2008 Aug 29
1
nls() fails on a simple exponential fit, when lm() gets it right?
...tedXyData(mCall[["x"]],LHS,data) aaa=0.01 #Just guess aaa=0.01 to start the fit bbb=min(xy$y) #Use the minimum y value as an initial guess for bbb value=c(aaa,bbb) names(value)=mCall[c("aaa","bbb")] return(value) } fmla=as.formula("~(aaa*log(x)+bbb)") SSlogarithmic=selfStart(fmla,initial=logarithmicInit,parameters=c("aaa","bbb")) exponenInit=function(mCall,LHS,data) { xy=sortedXyData(mCall[["x"]],LHS,data) r=0.01 #Just guess r=0.01 to start the fit A=min(xy$y) #Use the minimum y value as an initial guess for A value=c(...