Computing pi: machin like formula

[oceanmar]

Hi saw your video about computing. What about this

[osveliz]

It looks like that works. Sorry that I didn't respond when you posted this.

[oceanmar]

Thanks.

[oceanmar]

Actually im trying this formula in python. And it gives me roughly 2 decimal places wrong for example when i check up to 100 roughly 98 decimal correct last no. This is the formula i used deriving from the one i sent u earlier. Its the last formula.

[osveliz]

It looks like the 2arctan(1/4) and -2arctan(1/4) will cancel leaving with arctan(1) which will take a long time to converge.

[oceanmar]

Actually is yeah it would be like leibniz pi/4, but when i used this in python, to find n decimal places need n*2 iteration to have n-2 decimals correctly.
This is the alternative for arctan formula im using:

does this mean the big O: for this formula is O(n) and by using the equation above in the photo, ee can actually approximate pi by hand.