Some fun functions ...
plot(sin(-x)*pow(1.5,-r))
plot(pow(2,sin(y))*pow(2,sin(x))/12)
plot(sin(x*y/10)/10)
plot(sin(r)/r)
plot(tanh(x)+tanh(y))/3

search help using : helpful(search term) or for a specific functions : help(function)