I have a student in Y10 who can recite pi to 200 places, after listening to the pi song rather a lot of times … (see http://pi.ytmnd.com/). This led to reading more about how to calculate pi, and I found out about the Brent-Salamin algorithm, very clearly explained on Wikipedia. I tried it out on Excel, and also showed it to my Y13 students who really enjoyed it.
Here it is, so you don’t have to go to Wikipedia …
With my Y13 class we worked out pi to 6 decimal places in around 10 minutes, which they were impressed with.
I still want to know how calculators do things like sin and arcsin, or find square roots, so if anybody knows of a good link about this, please add a comment!
2 responses so far ↓
1
Ali
// May 20, 2008 at 9:03 am
It’s a lovely algorithm!, and it uses the arithmetic-geometric mean.
Apparently calculators calculate trig functions using something called the CORDIC algorithm, about which wikipedia has a page.
2
Ron Smith
// Jul 21, 2009 at 7:48 am
Nice article about pi calculation.
Leave a Comment