如何在 JavaScript 中提取 BigInt 的第 n 个根？

Question

如何在 JavaScript 中提取 BigInt 的 n 次方根？

Math.pow 无效。

Answer 1

转换为 JavaScript 的 BigInt 表示法，基于 from Java as suggested by Dai in the comments. Make sure that base and root that are passed in are BigInt's, if not then you can just set base = BigInt(base); etc. for the two inputs. This is based off of Newton's formula. Also, BigInt's can't represent decimals, so every division is floored division so this doesn't work for the cube root of 16, for example. Here's some Mozilla documentation of BigInt that is worth the read: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/BigInt

function iroot(base, root) {
  if (typeof base !== 'bigint' || typeof root !== 'bigint') throw new Error("Arguments must be bigints.");

  let s = base + 1n;
  let k1 = root - 1n;
  let u = base;
  while (u < s) {
    s = u;
    u = ((u*k1) + base / (u ** k1)) / root;
  }
  return s;
}

如何在 JavaScript 中提取 BigInt 的第 n 个根？

How do I extract the nth root of a BigInt in JavaScript?

javascript

biginteger