This example plots the data in the file "population.dat" and a theoretical curve:
pop(x) = 103*exp((1965-x)/10)
plot [1960:1990] 'population.dat', pop(x)
The file "population.dat" might contain:
# Gnu population in Antarctica since 1965
1965 103
1970 55
1975 34
1980 24
1985 10