All you need for the next recipe is to type it at the R prompt as we will only use some base functions. You can also save the recipe code as a script so that you can use it again later on.

Plot an exponential plot:

x <- -(1:100)/10
y <- 100 + 10 * exp(x / 2) + rnorm(x)/10
nlmod <- nls(y ~  Const + A * exp(B * x), trace=TRUE)

plot(x,y)
lines(x, predict(nlmod), col="red")

We first plot y against x, where x is a variable defined using the: sequence operator and y is an exponential function of x. Then, we fit a nonlinear model to the data using the nls() function. We save the model fit as nlmod and finally draw the model predicted values by passing x and predict(nlmod) to the lines() function.