Control.com - Nerds in Control

I've been looking at the C~C method but can't seem to get things to 'work'.

First: to determine t1. I sometimes end up with a negative number. That can't be right... Is the equation asking for the 'natural log' of '2' or 'log to the base 2' - the font that my equation is written in doesn't make it clear.

e.g. t1=(t2 - ln(2)t3)/(1 - ln(2))

2nd: t(tau)del. What time are they using; surely t0(zero) is just that - zero! from:

tdel = t1 - t0

tdel is always going to equal t1 if t0 is the point at which the error was introduced (and the clock was started so-to-speak)

What am I missing???

All help will be greatfully received - believe me...

Phineas