minor tweaks: include math.h; remove repeated definition of Time.
minor tweaks: include math.h; remove repeated definition of Time.
FranklinChen/Hugs,FranklinChen/Hugs,FranklinChen/Hugs,FranklinChen/Hugs,FranklinChen/Hugs,FranklinChen/Hugs,FranklinChen/Hugs