title: Java floating point high precision library
body: <p>Which libraries for Java are there that have a fast implementation for floating point or fixed point operations with a precision of several thousands of digits? How performant are they?</p>
  
  <p>A requirement for me is that it implements a multiplication algorithm that is better than the naive multiplication algorithm that takes 4 times as much time for a 2 times larger number of digits (compare <a href="http://en.wikipedia.org/wiki/Multiplication_algorithms" rel="noreferrer">Multiplication algorithms</a>).</p>