Can LAMMPS compute VACF or autocorrelation of other physical quantity in an approximate way?

Dear colleagues,

  I understand that `compute vacf command` can compute autocorrelation function for velocity based on the velocity data generated from simulation. I wonder whether or not LAMMPS uses any approximation scheme when computing vacf? I.e. if the simulation time is very long, is the vacf still computed based on the entire generated velocity history, or some subsampling or approximation scheme is used in computing vacf?

Many thanks,
Zhishen Huang

There is no approximation. LAMMPS will keep averaging the VACF vectors.