##### R and C++ mll should be the same:
[1] 275.6672
[1] 275.6672

&&&& time for vectorized R version
   user  system elapsed 
  5.932   0.004   5.933 

&&&& time for C++ version
   user  system elapsed 
  3.036   0.001   3.037 

$$$$$ difference in mll from R and C++
      Min.    1st Qu.     Median       Mean    3rd Qu.       Max. 
-3.809e-12 -1.137e-13  0.000e+00  4.600e-17  1.137e-13  3.809e-12