vectorised math library

 This is vectorised math library
  - a collection of fast and inline implementations of mathematical functions
  - the functions can be used in autovectorised loops
  - double and single precision implementations are available
  - no overhead present, no intrinsics used
 .
 A scalar (T(T)) and array signature (void(const unsigned int, T*, T*)) are
 provided. Born and developed at CERN, it is used, among the others, by LHC
 experiments and the Geant4 simulation toolkit.
 .
 Much of the VDT code is inspired by the well known Cephes mathematical
 library.