title: C++: convert "boost::multiprecision::float128" to "double"
body: <p>I'm using the boost multiprecision library, and more precisely the boost::multiprecision::float128 type. Using ICPC for compiling, I get some errors when trying to to do something like:</p>
  
  <pre><code>double a = functionA();
  </code></pre>
  
  <p>where functionA() return a boost::multiprecision::float128 variable.</p>
  
  <pre><code>error: no suitable conversion function from "boost::multiprecision::float128" to "double" exists|
  </code></pre>
  
  <p>How can I solve this?</p>