2-d graph of a 2-d function with colors : plotdensity densityplot

plotdensity(f(x,y),[x,y]) or densityplot(f(x,y),[x,y]) draws the graph of z = f (x, y) in the plane where the values of z are represented by the rainbow colors. The optional argument z=zmin..zmax specifies the range of z corresponding to the full rainbow, if it is not specified, it is deduced from the minimum and maximum value of f on the discretisation. The discretisation may be specified by optional xstep=... and ystep=... or nstep=... arguments.
Input :

plotdensity(x^2-y^2,[x=-2..2,y=-2..2], xstep=0.1,ystep=0.1)

Output :

A 2D graph where each hyperbola defined by x^2-y^2=z has a color from the rainbow

Remark : A rectangle representing the scale of colors is displayed below the graph.