[p5.js 2.0+ Bug Report]: 3x3 p5.Matrix.transpose() ignores passed matrix/array input and produces incorrect results

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Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
88/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Active
Tech stack
javascript
Domain
computer-graphics

Research direction

Start with p5.Matrix.transpose() and the skipped tests in test/unit/math/p5.Matrix.js. Reproduce both 3x3 calls using a matrix and an array, then make the behavior match the expected transposed values [1, 4, 7, 2, 5, 8, 3, 6, 9] and run the relevant matrix tests.

Written by the indexing model from the issue text.

Description

Area:Math p5.js 2.0+
Most appropriate sub-area of p5.js?
  • Accessibility
  • Color
  • Core/Environment/Rendering
  • Data
  • DOM
  • Events
  • Image
  • IO
  • Math
  • Typography
  • Utilities
  • WebGL
  • WebGPU
  • p5.strands
  • Build process
  • Unit testing
  • Internationalization
  • Friendly errors
  • Other (specify if possible)
p5.js version

No response

Web browser and version

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Operating system

No response

Steps to reproduce this

The p5.Matrix.transpose() method is incorrectly handling the 3x3 case when a source matrix or array is passed in.

Current implementation does not reliably transpose the supplied source matrix and can leave the result incorrect or inconsistent. The skipped tests already describe this expected behavior in test/unit/math/p5.Matrix.js.

Steps:
  1. Create a 3x3 matrix using new p5.Matrix([1, 2, 3, 4, 5, 6, 7, 8, 9])
  2. Call transpose() with the matrix itself or with a 3x3 array:
mat.transpose(mat)
mat.transpose([1, 2, 3, 4, 5, 6, 7, 8, 9])
  1. Compare the result to the expected transposed matrix [1, 4, 7, 2, 5, 8, 3, 6, 9]
Snippet:

const mat = new p5.Matrix([1, 2, 3, 4, 5, 6, 7, 8, 9]);

console.log(mat.transpose(mat).mat3);
// expected: [1, 4, 7, 2, 5, 8, 3, 6, 9]

console.log(mat.transpose([1, 2, 3, 4, 5, 6, 7, 8, 9]).mat3);
// expected: [1, 4, 7, 2, 5, 8, 3, 6, 9]

Can i be assigned this issue @limzykenneth @perminder-17

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