title: Undefined reference to log10?
body: <p>I have the following two functions and when compiling, I am face with the error in the title.</p>
  <pre><code>double getIdf(FileList fl, int D){
    double fileCount = countFiles(fl); //todo countfiles
    double temp = fileCount/D;
    double idf = log10(temp);
    return (fabs(idf));
  }
  
  double countFiles(FileList fl){
      if (fl == NULL){
          printf(&quot;countFiles FL does not exist\n&quot;);
          return 0;
      }
      double count = 0;
      FileList curr = fl;
      while (curr != NULL) {
          count++;
          curr = curr-&gt;next;
      }
      return count;
  }
  </code></pre>
  <p>However, if I change the log10 function to log10(5.5) it would work.</p>
  <pre><code>double getIdf(FileList fl, int D){
    double fileCount = countFiles(fl); //todo countfiles
    double temp = fileCount/D;
    double idf = log10(5.5);
    return (fabs(idf));
  }
  </code></pre>
  <p>I am compiling with -lm.</p>
  <p>Whats wrong here?</p>