Anyone plz give me a formula about how e6b calculate the caliberated airspeed

As we know, an e6b takes in three knowns---------temperature and pressure altitude, and true airspeed, to calculate the unknown----------caliberated airspeed. I've been trying to find a formula that describes how this function works, but all I found was how cas is related to mach number, pressure ratio, static pressure, stagnation pressure and lots of other fancy stuffs. I hope to program the function into matlab and I want it to be using the same inputs e6b is using, instead of the fancy stuffs. So plz show me such a formula, that describes how cas is calculated from the only 3 inputs,which are temperature, pressure altitude and true airspeed.

[John D'Errico]

Google is your friend.