| BOD {nls} | R Documentation |
Biochemical Oxygen Demand
Description
The BOD data frame has 6 rows and 2 columns giving the
biochemical oxygen demand versus time in an evaluation of water quality.
Arguments
Time |
A numeric vector giving the time of the measurement (days). |
demand |
A numeric vector giving the biochemical oxygen demand (mg/l). |
Format
This data frame contains the following columns:
Source
Bates and Watts (1998), Nonlinear Regression Analysis and Its Applications, Wiley, Appendix A1.4. Originally from Marske (1967), M.Sc. Thesis, University of Wisconsin - Madison.
Examples
library(nls)
data(BOD)
# simplest form of fitting a first-order model to these data
fm1 <- nls(demand ~ A*(1-exp(-exp(lrc)*Time)), data = BOD,
start = c(A = 20, lrc = log(.35)))
coef(fm1)
print(fm1)
# using the plinear algorithm
fm2 <- nls(demand ~ (1-exp(-exp(lrc)*Time)), data = BOD,
start = c(lrc = log(.35)), algorithm = "plinear", trace = TRUE)
# using a self-starting model
fm3 <- nls(demand ~ SSasympOrig(Time, A, lrc), data = BOD)
summary( fm3 )