Eigenvectors not reproducible between architectures
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- Macaulay2
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Description
The underlying problem behind #1631 is that `eigenvectors` produces different results on i386 and amd64. For example:
i386
----
```m2
i1 : (eigenvectors matrix {{6, 7, 9, 9, 5}, {2, 3, 3, 9, 3},
{8, 8, 9, 4, 2}, {9, 1, 9, 4, 9}, {2, 7, 8, 3, 4}})_1
o1 = | .550997 -.0294819 .375248 -.202898+.049597ii -.202898-.049597ii |
| .310498 -.507314 .486896 -.598172 -.598172 |
| .47751 .630015 -.673445 .30506+.339552ii .30506-.339552ii |
| .504279 .102214 -.200787 .161557-.550448ii .161557+.550448ii |
| .343044 -.578271 .358159 .24064+.0566015ii .24064-.0566015ii |
5 5
o1 : Matrix CC <--- CC
53 53
```
amd64
------
```m2
i1 : (eigenvectors matrix {{6, 7, 9, 9, 5}, {2, 3, 3, 9, 3},
{8, 8, 9, 4, 2}, {9, 1, 9, 4, 9}, {2, 7, 8, 3, 4}})_1
o1 = | .550997 -.0294819 .375248 .202898-.049597ii .202898+.049597ii |
| .310498 -.507314 .486896 .598172 .598172 |
| .47751 .630015 -.673445 -.30506-.339552ii -.30506+.339552ii |
| .504279 .102214 -.200787 -.161557+.550448ii -.161557-.550448ii |
| .343044 -.578271 .358159 -.24064-.0566015ii -.24064+.0566015ii |
5 5
o1 : Matrix CC <--- CC
53 53
```
The first three columns are identical, but the last two have opposite signs from one another.
Contributor guide
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First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
No source file or test is identified in the issue. Start by reproducing the reported eigenvectors example on i386 and amd64, then trace the eigenvectors entry point to find the architecture-dependent sign choice; done means the result follows a consistent documented convention on both architectures.
Written by the indexing model from the issue text.
Assessment
- Domain
- tooling
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 35/100