10-27-2012 01:25 PM - edited 10-27-2012 01:28 PM
I think I have misunderstood this question. .
If your screen is 1 inch square, and has 100 pixels in each dimension, then the dpi is just 100 dpi.
Obviously a real screen has different dimension and different pixels but you can use this sort of mathematics to do the calculation.
if this doesn't help, can you ask your question a different way?
Edit: Just found a similar Thread/question you have asked:
See more there.: