title: Understanding the working of logb()
body: <p>I am trying to understand the working of  <code>logb()</code> , It's <a href="http://www.mkssoftware.com/docs/man3/logb.3.asp" rel="nofollow">manual</a> says "<strong>The logb() function computes exponent of x, which is the integral part of $ \log_r^{|x|} $, as a signed floating point value, for a non-zero x, <em>where r is the radix of the machine's floating-point</em> arithmetic."</strong></p>
  
  <p>I am inquisitive to know to compute this <code>r</code> for a particular machine ?</p>