So I just purchased this software for my Iphone and I'm trying to figure out what the "Y intercept" is all about. Can anyone help me out with this?

from thier website: "Y-Intercept: The desired drop (or rise) to compute at zero range. This is normally zero. "

Thanks for that. I didn't think of searching for a website. So would it be safe to say that if you zeroed at 100yrds and entered 100yrd for the zero into the software but your bullet hits 1" high at 100 you would enter 1" for the y intercept?