/* * PI computation in Javascript using the QuickJS bigfloat type * (binary floating point) */"use strict"; /* compute PI with a precision of 'prec' bits */function calc_pi() {    const CHUD_A = 13591409n;    const CHUD_B = 545140134n;    const CHUD_C = 640320n;    const CHUD_C3 = 10939058860032000n; /* C^3/24 */    const CHUD_BITS_PER_TERM = 47.11041313821584202247; /* log2(C/12)*3 */        /* return [P, Q, G] */    function chud_bs(a, b, need_G) {        var c, P, Q, G, P1, Q1, G1, P2, Q2, G2;        if (a == (b - 1n)) {            G = (2n * b - 1n) * (6n * b - 1n) * (6n * b - 5n);            P = BigFloat(G * (CHUD_B * b + CHUD_A));            if (b & 1n)                P = -P;            G = BigFloat(G);            Q = BigFloat(b * b * b * CHUD_C3);        } else {            c = (a + b) >> 1n;            [P1, Q1, G1] = chud_bs(a, c, true);            [P2, Q2, G2] = chud_bs(c, b, need_G);            P = P1 * Q2 + P2 * G1;            Q = Q1 * Q2;            if (need_G)                G = G1 * G2;            else                G = 0l;        }        return [P, Q, G];    }     var n, P, Q, G;    /* number of serie terms */    n = BigInt(Math.ceil(BigFloatEnv.prec / CHUD_BITS_PER_TERM)) + 10n;    [P, Q, G] = chud_bs(0n, n, false);    Q = Q / (P + Q * BigFloat(CHUD_A));    G = BigFloat((CHUD_C / 12n)) * BigFloat.sqrt(BigFloat(CHUD_C));    return Q * G;} (function() {    var r, n_digits, n_bits;    if (typeof scriptArgs != "undefined") {        if (scriptArgs.length < 2) {            print("usage: pi n_digits");            return;        }        n_digits = scriptArgs[1];    } else {        n_digits = 1000;    }    n_bits = Math.ceil(n_digits * Math.log2(10));    /* we add more bits to reduce the probability of bad rounding for       the last digits */    BigFloatEnv.setPrec( () => {        r = calc_pi();        print(r.toFixed(n_digits, BigFloatEnv.RNDZ));    }, n_bits + 32);})();