title: Linking with gcc and -lm doesn't define ceil() on Ubuntu
body: <p>I am currently using gcc to compile and I need to use <code>&lt;math.h&gt;</code>.
  Problem is that it won't recognize the library.
  I have also tried <code>-lm</code> and nothing.
  The function I tried to use was <code>ceil()</code> and I get the following error:</p>
  
  <pre><code>: undefined reference to `ceil'
  collect2: ld returned 1 exit status
  </code></pre>
  
  <p>I am using the latest Ubuntu and math.h is there.
  I tried to use <code>-lm</code> in a different computer and it work perfectly.</p>
  
  <p>Does anyone know how to solve this problem?</p>
  
  <hr>
  
  <p>I did include <code>&lt;math.h&gt;</code>.  Also, the command I used was:</p>
  
  <pre><code>gcc -lm -o fb file.c
  </code></pre>