Up to now we've concentrated on computing areas by integrating the constant 1 over some domain. If we want the volume over a domain and beneath an arbitrary surface graph, we just need to integrate the function whose graph is the surface.
Earlier in this lab, we modeled the Metrodome by elliptical walls and a roof that was a quartic polynomial. Numerically estimate the volume of this model of the Metrodome by
leftbox2d(roof,x=-2..2,y=-1..1, grid=[10,10], region=-M..M);
The volume is being estimated by rectangular blocks. The height of a block is the height of the roof over the lower left corner of the corresponding rectangle on the grid.