Q:

Higher precision doubles and trigonometric functions in Java

According to IEEE the following doubles exist:
                Mantissa   Exponent  
double 64bit:       52 bit     11 bit  
double 80bit:       64 bit     15 bit  

In Java only the 64bit double can be directly
stored in an instance variable. I would like for 
whatever reason work with 80bit floats as defined 
above in Java. I am interested in the full set 
of arithmetic functions, I/O and trigonometric
functions. How could I do that? 
One could of course do something along the 
following lines:
public class DoubleExt {
    private long mantissa;
    private short exponent;
}

And then make a package that interfaces with
some of the known C libs for 80bit floats.
But would this be considered the best practice? 
What about supporting a couple of plattforms
and architectures?
Bye

A:

I'm pretty sure primitives won't get you there, but the BigDecimal class is as good as it gets (for everything except trigonometry).
For trigonometric functions, however, you will have to resort to an external library, like APFloat (see this previous question).

