Concentration<-c(6.2,6.1,5,4.9,3.7,3.8,3.8,3.9,3.6,3.5,3.9,3.6) Distance<-c(5,5,15,15,25,25,32,32,42,42,55,55) b0start <- max(Concentration) b1start <- -log(1/b0start) b2start <- (max(Concentration) - min(Concentration)) / (max(Distance) - min(Distance)) / b0start mystart<-c(b0=b0start,b1=b1start,b2=b2start) model_exponential <- nls(y ~ a * exp(-b * x), data = Concentration, start = list(a = 0, b = 1)) Error in nls(y ~ a * exp(-b * x), data = Concentration, start = list(a = 0, : 'data' must be a list or an environment
I want to run an exponential decay model for Distance and Cconcentration but it is giving an error
Concentration<-c(6.2,6.1,5,4.9,3.7,3.8,3.8,3.9,3.6,3.5,3.9,3.6) Distance<-c(5,5,15,15,25,25,32,32,42,42,55,55) b0start <- max(Concentration) b1start <- -log(1/b0start) b2start <- (max(Concentration) - min(Concentration)) / (max(Distance) - min(Distance)) / b0start mystart<-c(b0=b0start,b1=b1start,b2=b2start) model_exponential <- nls(y ~ a * exp(-b * x), data = Concentration, start = list(a = 0, b = 1)) Error in nls(y ~ a * exp(-b * x), data = Concentration, start = list(a = 0, : 'data' must be a list or an environment