New functions CountRoots, IsolatingInterval, and RootIntervals have been added to the built-in Mathematica kernel. IsolatingInterval includes the functionality of ContractInterval from Version 5.2. RootIntervals incorporates the functionality of RealRootIntervals and ComplexRootIntervals from Version 5.2.
CountRoots now counts roots in closed intervals; in Version 5.2, it used open intervals: