Volume Under Surface command

hchanson · Post by **hchanson** » Tue Jan 29, 2019 11:42 pm

I am not sure to understand the "Volume Under Surface command " and the Help file. The help file for that command show a graph. Two result windows are shown for the same graph. Since it is the same curve, the total volume (above + below) should be the same irrespective of the specified Z. Is it not?
Thank you in advance for any hint, as the Help is very succint.

Post by **DPlotAdmin** » Wed Jan 30, 2019 2:07 am

Since it is the same curve, the total volume (above + below) should be the same irrespective of the specified Z. Is it not?

The short answer is "no". Imagine if the reference Z was, instead of -1, -100. The volume below will still be 0, The volume above is a large(r) number, which is correct.

It might help you to visualize this operation with a 2D curve and integrating it. The sum of the areas above and below some reference Y will NOT be the same for different reference Y's.