Quotes About Floating-point

Version 1.3, Java has allowed for extended precision on platforms that support it. This can introduce extremely small-valued and arcane differences in the results of high-precision operations. Most applications would never notice this, but if you want to ensure that your application produces exactly the same results on different platforms, you can use the special keyword strictfp as a class modifier on the class containing the floating-point manipulation

Choosing the right precision for a problem where the choice matters requires significant understanding of floating-point computation. If you don't have that understanding, get advice, take the time to learn, or use double and hope for the best.