Please do create a text version of how does a calculation works.

[fingersandmind]

As a student practicing php language, can you provide a text version of the formula for this one?

[nikolaygekht]

:-) You are asking me to write yet another book on external ballistics.

I would rather suggest to:

1. Read and follow the links from Wiki pages on external ballistics on the first page of the documentation:
   http://docs.gehtsoftusa.com/BallisticCalculator1/#main.html

   The core of the algorithm is a simple 3 degree of force simulation (quantization of inertial movement of a body in 3-dimension
   space) (read more about 3/6DF here https://en.wikipedia.org/wiki/Six_degrees_of_freedom). 99% of magic is in how the
   velocities change through the time under influence of drag force, wind and gravity.

2. There is also an approximation of bullet precession and influence of Coriolis performed using the formulas described by a recognized guru in external ballistic Brian Litz and described in his book "Applied Ballistics".

   I am afraid that without reading all of these any "short" explanation will be hard to understand.