C++ - MPIR: Fastest Log Function?
<p>MPIR is a really good library that I am currently using in C++ to deal with large numbers. Unfortunately, it does not have any log functions. Because of that, I am seeking a fast log function for MPIR's mpz_class.</p>

<p>We are all well aware of the fact that there are some log functions that are already provided in C++ (or should be), which are located in the Math header file (Math.h). Unfortunately, they can not handle big numbers, which is one of the many reasons why I am using MPIR library,</p>

<pre><code>::mpz_class Log( ::mpz_class n ) {
    ::mpz_class ret;
    return ret;
};
</code></pre>

<p>There are some cases in which the log of n returns floating value. Hence, our log function must be able to return a floating value. If we were to do the Log of 15, it should return 1.17609125906.</p>
