Programming Tips - bc: calculate pi to an unlimited number of digits

Date: 2020sep28 Product: bc OS: Linux Keywords: π, arbitrary precision calculator language Q. bc: calculate pi to an unlimited number of digits A.
echo 'scale=1000; 4*a(1)' | bc -lq
scale is the number of digits. a() = arctan() arccos(-1) is also pi but bc doesn't support it.