The rint functions return the nearest integral value to x in
    the direction of the current IEEE rounding mode specified on the
    /ROUNDING_MODE command-line qualifier.

    If the current rounding mode rounds toward negative Infinity,
    then rint is identical to floor. If the current rounding mode
    rounds toward positive Infinity, then rint is identical to ceil.

    If |x| = Infinity, rint returns x.