This demo displays a cylindrical wireframe domain colored according to the value of the function.  A region enclosed within a surface in this domain is also colored according to the value of the function, and this surface is determined by the variables "stepR", "stepT", and "stepZ" which determine the maximum r, t, and z of the surface respectively.

The readout "M" gives the total mass of the region enclosed by the surface.  Regardless of which order the variables are manipulated, if they all have the same value they will yield the same result for the readout "M" demonstrating that changing the order of integration does not affect the result.