I have a bit of code from a textbook I am looking to understand for interpolation search, it says:

next= low + |(x-a[low]/a[high]-a[low])*(high-low-1)|

the | are ceiling.

I understand what it does in finding the estimated location based on the percentage given by the division, I was just wondering why low is added to it after an estimated point is found, it doesnt even specify what low is in the text. Thanks for any help you can give me.