2014-03 – Functions like round() and nearbyint() are in the xc32 mplab help but don't appear to actually exist when compiling?
From support: Functions round() and nearbyint() are from Dinkumware C++ libraries packaged along with C++ compiler. The Dinkum Complete Libraries are a collection of several C++ libraries, all based on ISO standards. You can use these functions with C++ compiler.
2014-03 – Function rint() doesn't work.
From support: confirmed that broken and will be fixed in future release