# Sparse linear algebra question lu(::SparseMatrixCSC)

**URL:** <https://discourse.julialang.org/t/sparse-linear-algebra-question-lu-sparsematrixcsc/62625>\
**Category:** General Usage\
**Tags:** linearalgebra, sparse\
**Created:** [June 9, 2021, 1:59pm UTC](https://discourse.julialang.org/t/sparse-linear-algebra-question-lu-sparsematrixcsc/62625 "2021-06-09T13:59:00Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![Thomas](https://avatars.discourse-cdn.com/v4/letter/t/e36b37/32.png) [@Thomas](https://discourse.julialang.org/u/Thomas)\
**Post date:** [June 9, 2021, 1:59pm UTC](https://discourse.julialang.org/t/sparse-linear-algebra-question-lu-sparsematrixcsc/62625/1 "2021-06-09T13:59:00Z")

</div>

I got this strange error

> using SparseArrays  
> M = sprand(3,16,0.5)  
> lu(M)  
> lu(M’)  
> ERROR: MethodError: no method matching lu!(::SparseMatrixCSC{Float64, Int64}, ::Val{true}; check=true)

Does anybody know why?

---

<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:** [June 9, 2021, 2:44pm UTC](https://discourse.julialang.org/t/sparse-linear-algebra-question-lu-sparsematrixcsc/62625/2 "2021-06-09T14:44:07Z")

</div>

Looks like a missing method: [missing lu(::SparseMatrixCSC, ::Val{true}; ...) method · Issue #41154 · JuliaLang/julia · GitHub](https://github.com/JuliaLang/julia/issues/41154)

As a workaround, you can simply use `lu(M)'` instead of `lu(M')`.

---

<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:** [June 10, 2021, 2:19am UTC](https://discourse.julialang.org/t/sparse-linear-algebra-question-lu-sparsematrixcsc/62625/3 "2021-06-10T02:19:27Z")

</div>

2 posts were split to a new topic: [Computing sparse orthogonal projections](https://discourse.julialang.org/t/computing-sparse-orthogonal-projections/62652)