mathjs/src/type/bignumber/function/bignumber.js

import { factory } from '../../../utils/factory'
import { deepMap } from '../../../utils/collection'

const name = 'bignumber'
const dependencies = ['typed', 'BigNumber']

export const createBignumber = /* #__PURE__ */ factory(name, dependencies, ({ typed, BigNumber }) => {
  /**
   * Create a BigNumber, which can store numbers with arbitrary precision.
   * When a matrix is provided, all elements will be converted to BigNumber.
   *
   * Syntax:
   *
   *    math.bignumber(x)
   *
   * Examples:
   *
   *    0.1 + 0.2                                  // returns number 0.30000000000000004
   *    math.bignumber(0.1) + math.bignumber(0.2)  // returns BigNumber 0.3
   *
   *
   *    7.2e500                                    // returns number Infinity
   *    math.bignumber('7.2e500')                  // returns BigNumber 7.2e500
   *
   * See also:
   *
   *    boolean, complex, index, matrix, string, unit
   *
   * @param {number | string | Fraction | BigNumber | Array | Matrix | boolean | null} [value]  Value for the big number,
   *                                                    0 by default.
   * @returns {BigNumber} The created bignumber
   */
  const bignumber = typed('bignumber', {
    '': function () {
      return new BigNumber(0)
    },

    number: function (x) {
      // convert to string to prevent errors in case of >15 digits
      return new BigNumber(x + '')
    },

    string: function (x) {
      return new BigNumber(x)
    },

    BigNumber: function (x) {
      // we assume a BigNumber is immutable
      return x
    },

    Fraction: function (x) {
      return new BigNumber(x.n).div(x.d).times(x.s)
    },

    null: function (x) {
      return new BigNumber(0)
    },

    'Array | Matrix': function (x) {
      return deepMap(x, bignumber)
    }
  })

  return bignumber
})