Uncertainty String

A module for handling physics-style uncertainty-strings, like 1.873(34). You can see it in action in this playground: https://mj-h.github.io/uncertainty-string/

Install with

npm install uncertainty-string

Usage:

const { UncertaintyString } = require("uncertainty-string")

let [value, uncertainty] = UncertaintyString.toNumbers("1.234(56)");
// -> value       = 1.234
//    uncertainty = 0.056

let uncertstr = UncertaintyString.fromNumbers(0.789, 0.015);
// -> uncertstr = 0.789(15)

Background

In physics, it is customary to always state the measurement-uncertainty together with the measurement. For example: "The length of this stick is 1.235 meters plus or minus 0.022 meters". Since this is cumbersome, the following shorthand is often used: "The length of this stick is 1.234(22) meters".

Some debate exists over including the decimal point in the uncertainty:

• with decimal-point: 45.6(2.3)
• without decimal-point: 45.6(23) Some journals use the decimal-point, others don't. This module follows the convention used by Physical Review Letters and omits the decimal point (see page 1 of this article)

Examples

• "123(15)"
  • mean: 123
  • uncertainty: 15
• "12.3(15)"
  • mean: 12.3
  • uncertainty: 1.5
• "1.23(15)"
  • mean: 1.23
  • uncertainty: 0.15
• "0.123(15)"
  • mean: 0.123
  • uncertainty: 0.015
• "1230(150)"
  • mean: 1230
  • uncertainty: 150
• "12300(1500)"
  • mean: 12300
  • uncertainty: 1500

For a full list of examples, see the test file or play with UncertaintyString on the playground