Riemann sum model for the multivariable "sombrero" function
This model shows the rectangular prisms (49 x 49) that make up the Riemann sum approximation to the integral of the "sombrero" function f(x,y) = exp(-k sqrt(x² + y²)) cos(sqrt(x² + y²)).
I have also included the OpenSCAD file, which is set up so you can modify the function or parameters to produce your own model.