This Fractal Time Calculator is MUCH MORE ACCURATE than Gregg's online calculator or the calculations of the book!
The logic used by Gregg Braden is perfect and sound, unfortunately there are two errors in the formula:
Anyway, you can manually input any 4-digit number as Calendar Difference.
For the sake of clearance I will go through the book example, starting bottom of page 211 with the "surprise attack upon America":
The first inaccuracy is in the seed date and occurs for using the estimates "zones of time" of page 209-210, for December is equal to the value .99 and as you clearly can see, the accurate calculation of the latest day in December will return .973 and calculate to the 4th of August 1984 - which is still within the prediction of the book.
Now, using 3112 years calendar difference (instead of 3113), let's start the accurate example of the Pearl Harbor incident, dated: 1941-December-07
The proper result date, using a Seed Date of 1941.908 (instead of 1941.99 from the book) is 1985-February-26 (instead of August 1984 from the book)
This is the most accurate calculator for time loops available.