|Katie: Questions Re. your "99 digits of Pi" article|
Message #1 Posted by W. Bruce Maguire II on 19 June 2002, 7:33 p.m.
Katie (or whoever may provide some answers):
Could you please elucidate on a few points for me?
In your "99 digits of Pi" article, there are a few points in the program that I don't follow. I have not invested a lot of time trying to figure it out, so please excuse me if the questions are dumb.
First, I don't understand your series expansion for ArcTan. What is the "y" in the formula; where did it come from?
Second, how are the "starting values" of 280,000,000 and 30,336,000 computed (I think I understand the method of numeric storage). Are these first-term values for the ArcTan(1/7) and ArcTan(3/79)?
Third, where does the "divide by 50" come from in Subroutine 'X'?
Fourth, where does the "multiply by 9 and divide by 125" come from in Subroutine 'R'?
I have not carefully re-enacted the register manipulations in the routines, but I think that your documentation will be quite sufficient for me to understand all the data manipulation. But after my cursory examination, I was confused on the four points listed above. Thanks in advance for any help!