Function _round

banking/src/lib/numbers.ts:167–221

(num: number, precision: number, rounding_method?: string)

}

const _round = (num: number, precision: number, rounding_method?: string) => {

    rounding_method = rounding_method || getSystemDefault('rounding_method') || "Banker's Rounding (legacy)";

    const is_negative = num < 0 ? true : false;

    if (rounding_method == "Banker's Rounding (legacy)") {
        const d = cint(precision);
        const m = Math.pow(10, d);
        const n = +(d ? Math.abs(num) * m : Math.abs(num)).toFixed(8); // Avoid rounding errors
        const i = Math.floor(n),
            f = n - i;
        let r = !precision && f == 0.5 ? (i % 2 == 0 ? i : i + 1) : Math.round(n);
        r = d ? r / m : r;
        return is_negative ? -r : r;
    } else if (rounding_method == "Banker's Rounding") {
        if (num == 0) return 0.0;
        precision = cint(precision);

        const multiplier = Math.pow(10, precision);
        num = Math.abs(num) * multiplier;

        const floor_num = Math.floor(num);
        const decimal_part = num - floor_num;

        // For explanation of this method read python flt implementation notes.
        const epsilon = 2.0 ** (Math.log2(Math.abs(num)) - 52.0);

        if (Math.abs(decimal_part - 0.5) < epsilon) {
            num = floor_num % 2 == 0 ? floor_num : floor_num + 1;
        } else {
            num = Math.round(num);
        }
        num = num / multiplier;
        return is_negative ? -num : num;
    } else if (rounding_method == "Commercial Rounding") {
        if (num == 0) return 0.0;

        const digits = cint(precision);
        const multiplier = Math.pow(10, digits);

        num = num * multiplier;

        // For explanation of this method read python flt implementation notes.
        let epsilon = 2.0 ** (Math.log2(Math.abs(num)) - 52.0);
        if (is_negative) {
            epsilon = -1 * epsilon;
        }

        num = Math.round(num + epsilon);
        return num / multiplier;
    } else {
        throw new Error(`Unknown rounding method ${rounding_method}`);
    }
}


export const cint = (v: boolean | string | number, def?: boolean | string | number) => {