My problem: I calculate, using Differential Geometry, the surface area of a specific part to be 50% more than the surface area AutoCAD calculates it to be using the AREA command on an extruded solid. I am certain that my calculations are correct. I use theorems of Differential Geometry that apply to piece-wise differentiable surfaces and said part is piece-wise differentiable. I have had my calculations double-checked by a colleague and verified by an independent calculation, so I am certain there are no typographical or algebraic errors. I used wolfram alpha to run the arithmetic in obtaining the final value. My Question: I would really like to be able to account for the deviation between my calculation and AutoCAD's. If anyone has any general information about the algorithm used in AutoCAD's AREA command, enough information that a Physics major who (barely) passed the undergraduate and graduate Differential Geometry courses could determine if such an algorithm applies to said part, I would be very grateful. Note: I have produced a (sloppy) proof that their exists no equiareal mapping from the surface of said part to any of the common primitives.