Thin SVD

Open
#414 0 comments 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
38/100
Issue type
Feature
Clarity
Mostly clear
Activity status
Stale
Tech stack
rust

Research direction

Start by reading lax/src/svd.rs, especially the SvdWork implementation and the documented LAPACK operation table, then compare the entry point in lax/src/lib.rs with the SVD trait in ndarray-linalg/src/svd.rs. Determine how the gesvdx-based thin or economy SVD should fit the existing API; done means the capability is implemented and its supported operation documentation is updated.

Written by the indexing model from the issue text.

Description

I was studying PICARD (a faster version of ICA than "FastICA") and saw some mention of various types of SVD, which I'm already familiar with. One of the variants was "thin" SVD. I can see that there are other libs that save computation by only computing this "thin" variant and I was wondering if maybe ndarray-linalg could too.

I did a search of the code earlier and saw no mention of it, I'm curious if it'd be worth developing.

My understanding is that there are separate LAPACK functions/instructions you'd use for 'economy'/'thin' SVD, gesvdx being the relevant one

For reference I am interested in its use in whitening in this crate

So two things I see there are that

  1. there's this line saying it is unimplemented

https://github.com/rust-ndarray/ndarray-linalg/blob/49e964be06c830a04442e48e0f9a89d2000bbbd1/lax/src/svd.rs#L63-L67

  1. there's this comment making v clear which LAPACK instructions are supported

https://github.com/rust-ndarray/ndarray-linalg/blob/49e964be06c830a04442e48e0f9a89d2000bbbd1/lax/src/svd.rs#L6-L8

and (from right to left in that table)

https://github.com/rust-ndarray/ndarray-linalg/blob/49e964be06c830a04442e48e0f9a89d2000bbbd1/lax/src/svd.rs#L180-L181

https://github.com/rust-ndarray/ndarray-linalg/blob/49e964be06c830a04442e48e0f9a89d2000bbbd1/lax/src/svd.rs#L313-L314

I'd be interested in this but for now just pointing out where the relevant parts of code are, have not dug deeper! 👍

Dominant language
Rust
Stars
452
Forks
95
PR merge metrics
No merged PRs in 30d

Contributor guide

No contributing guide indexed for this repository

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

More from rust-ndarray/ndarray-linalg

All issues in rust-ndarray/ndarray-linalg

Similar issues

More Rust issues

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.