What would you like to draw?  


A function of one variable  y = f(x) 
A parametrically defined curve  (x(t), y(t)) 
A solution to a polynomial equation  p(x,y) = 0 


A function of two variable  y = f(x,y) 
A parametrically defined tube  (x(t), y(t), z(t)) 
A parametrically defined surface  (x(u,v), y(u,v), z(u,v)) 