mathjs/src/entry/configReadonly.js

import { DEFAULT_CONFIG } from '../core/config'
import { MATRIX_OPTIONS, NUMBER_OPTIONS } from '../core/function/config'

// create a read-only version of config
export const config = /* #__PURE__ */ function (options) {
  if (options) {
    throw new Error('The global config is readonly. \n' +
      'Please create a mathjs instance if you want to change the default configuration. \n' +
      'Example:\n' +
      '\n' +
      '  import { create, all } from \'mathjs\';\n' +
      '  const mathjs = create(all);\n' +
      '  mathjs.config({ number: \'BigNumber\' });\n')
  }

  return Object.freeze(DEFAULT_CONFIG)
}
Object.assign(config, DEFAULT_CONFIG, { MATRIX_OPTIONS, NUMBER_OPTIONS })