Approximate pi to 24 digits via keyboard

[Rick314]

(02-01-2015 08:41 AM)J-F Garnier Wrote:  This behavior is well known and has been discussed in the past, see for instance here.

Thanks, and possibly they learned it from my post to Usenet group alt.math.recreational about 10 months earlier here. I don't know if I was the first person to discover it, but did come up with it on my own. I was just recently looking at another thread in this forum and thought to share it here. I would be interested in related postings before 10/27/03 that you can find.

I see now we mean the same thing by "internal value of pi" and "the sin(x) algorithm". The algorithm uses an extended precision approximation to pi. I think most important is that the firmware designers recognized the need of doing something special to provide a full calculator precision answer to sin(x) when x is close to pi. I think others just missed the whole issue.

Thanks to all those following up. Math is fun!