Pi in Javascript

This Javascript program: pi_bigint.js computes hundreds of millions of digits of π using the Chudnovsky series. It assumes that the Javascript engine efficiently computes with large BigInt numbers, which is the case of QuickJS.

Time to compute 100 000 digits of π on a Core i5 4570 CPU at 3.2 GHz:

Spider Monkey
(version C70.0a1)
(version 7.7.289)
100 000 0.26 s 3.6 s 2.3 s

Of course it is not really fair because the other engines do not seem to have optimized the BigInt operations on large numbers.

Similar programs can be written using the BigFloat (binary floating point) or BigDecimal (decimal floating point) QuickJS extensions: pi_bigfloat.js and pi_bigdecimal.js. Run them with:

qjs --bignum pi_bigfloat.js 1e6
Here is the time to compute up to one billion digits of π with QuickJS:

100 000 0.12 s 0.26 s 2.1 s
1000 000 1.4 s 3.6 s -
10 000 000 19.1 s 56.0 s -
100 000 000 275 s - -
1000 000 000 3635 s - -

The BigFloat program is faster because the BigFloat square root is optimized in C while it is implemented in Javascript with a simple algorithm in the BigInt case.

The BigDecimal version is currently much slower because QuickJS does not optimize the operations on large BigDecimal numbers.