josdejong/mathjs

[BUG] error when handling coefficients with fractions

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#2,594 opened on Jun 11, 2022

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Description

Steps to reproduce:

  1. URL encode simplify('w/5-(2w+3)/2-3w/5') to simplify%28%27w%2F5-%282w%2B3%29%2F2-3w%2F5%27%29 using any URL encoder (I used https://www.urlencoder.io/).
  2. Hit https://api.mathjs.org/v4/?expr=simplify%28%27w%2F5-%282w%2B3%29%2F2-3w%2F5%27%29 in the address bar in any web browser (I'm using Google Chrome).
  3. Got output w * -2 / 5 + (-(2 * w) - 3) / 2.

Expected output: $$\frac{w}{5}-\frac{2w+3}{2}-\frac{3w}{5} = -\frac75w-\frac32$$

Contributor guide

Research direction
Inspect the simplify function in the source code, particularly how it handles fractional coefficients. Look at the expression parsing and simplification steps to identify where the sign or coefficient transformation goes wrong.
Tech stack
javascript
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
JavaScriptmath library usage
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40