title: error: 'mutex' in namespace 'std' does not name a type
body: <p>I am trying to use &quot;<strong>Armadillo
  C++ library for linear algebra &amp; scientific computing&quot;</strong> to compute the square root of a matrix. I am using JetBrains Clion ide to compute it.
  I am stuck at the error:
  <a href="https://i.stack.imgur.com/OWGFq.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/OWGFq.png" alt="enter image description here" /></a></p>
  <p>I went through these links already:</p>
  <p>1.) <a href="https://stackoverflow.com/questions/14191566/c-mutex-in-namespace-std-does-not-name-a-type">C++ mutex in namespace std does not name a type
  </a></p>
  <p>2.) <a href="https://stackoverflow.com/questions/36083003/error-mutex-does-not-name-a-type">error: 'mutex' does not name a type
  </a></p>
  <p>3.) <a href="https://stackoverflow.com/questions/14191566/c-mutex-in-namespace-std-does-not-name-a-type">C++ mutex in namespace std does not name a type</a></p>
  <p>I already have installed the <strong>pthreads</strong> package tried different flags but I am not able to resolve it. I am using MingW as :</p>
  <p><a href="https://i.stack.imgur.com/HRL3h.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/HRL3h.png" alt="enter image description here" /></a></p>
  <p>Any help will be appreciated. Thank you.</p>