title: -NaN in printf in C
body: <p>I am currently experiencing issues with a Raytracer "Engine" in some calculations.</p>
  
  <pre><code>  info-&gt;eyex = -1000.0;
    info-&gt;eyey = 0.0;
    printf("%f et %f et %f et %f et %f\n", info-&gt;eyex, info-&gt;vx, info-&gt;eyey, info-&gt;vy, info-&gt;vz);
  </code></pre>
  
  <p>For example, in that piece of code, values seems good, but <code>info-&gt;eyex</code> gives me a <code>-nan</code> error.</p>
  
  <p>It's weird, because I reset the value before.</p>