# Execution hangs indefinitely when trying to access QR factor

**URL:** <https://discourse.julialang.org/t/execution-hangs-indefinitely-when-trying-to-access-qr-factor/57881>\
**Category:** General Usage\
**Created:** [March 24, 2021, 5:10pm UTC](https://discourse.julialang.org/t/execution-hangs-indefinitely-when-trying-to-access-qr-factor/57881 "2021-03-24T17:10:54Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![iamsuddhasattwa](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/iamsuddhasattwa/32/7441_2.png) [@iamsuddhasattwa](https://discourse.julialang.org/u/iamsuddhasattwa)\
**Post date:** [March 24, 2021, 5:10pm UTC](https://discourse.julialang.org/t/execution-hangs-indefinitely-when-trying-to-access-qr-factor/57881/1 "2021-03-24T17:10:54Z")

</div>

The Qr factorization of an NXL matrix does not produce a NXL orthogonal matrix Q but an NXN matrix. When I try to access the first L columns, the execution hangs indefinitely.

```julia
using ArnoldiMethod;
using LinearAlgebra;
L = 200; N = 5000; Y = rand(N,L);
(Qc,Rc) = ArnoldiMethod.qr(Y);
Q = Qc[:,1:L];

```

At this point the execution hangs indefinitely.