[math] Formatting Infinities and NaN in exception messages

[Phil Steitz]

Researching MATH-414, I am seeing this stacktrace:

org.apache.commons.math.ConvergenceException: Continued fraction diverged to
NaN for value ?
    at
org.apache.commons.math.util.ContinuedFraction.evaluate(ContinuedFraction.java:186)

The "?" should represent positive infinity (the actual parameter passed to
the exception constructor).  Any ideas on how we can modify our framework to
support formatting infinities and NaNs?

Phil