A function f:R2→R maps a pair of values (x,y) to a single real number. The three-dimensional coordinate system we have already used is a convenient way to visualize such functions: above each point ...A function f:R2→R maps a pair of values (x,y) to a single real number. The three-dimensional coordinate system we have already used is a convenient way to visualize such functions: above each point (x,y) in the x - y plane we graph the point (x,y,z) , where of course z=f(x,y).
