# Matrix division \\ for sparse and singular matrices

**URL:** https://discourse.julialang.org/t/matrix-division-for-sparse-and-singular-matrices/68253
**Category:** General Usage
**Tags:** linearalgebra, sparse
**Created:** [September 16, 2021, 10:52am UTC](https://discourse.julialang.org/t/matrix-division-for-sparse-and-singular-matrices/68253 "2021-09-16T10:52:36Z")
**Posts on this page:** 1
**Showing post:** 6

<div class="post-metadata">

### Author: ![stevengj](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/stevengj/32/71_2.png) [@stevengj](https://discourse.julialang.org/u/stevengj)
#### Post date: [September 16, 2021, 1:07pm UTC](https://discourse.julialang.org/t/matrix-division-for-sparse-and-singular-matrices/68253/6 "2021-09-16T13:07:41Z")

</div>

> [@Why does julia systematically fails when doing \\ operation?](https://discourse.julialang.org/t/why-does-julia-systematically-fails-when-doing-operation/67242/9):
>
> In such situations, SVD is your friend

QR is a _much_ cheaper way to get least-square solutions of singular/nonsquare systems: `qr(A) \ b`

Also, QR works for sparse matrices too.

---

_[View the full topic](https://discourse.julialang.org/t/matrix-division-for-sparse-and-singular-matrices/68253)._