How to evaluate multiple frames with the C++ interface?

[cihe13375]

In C++ API doc (e.g. link) it's stated that the coord and box parameters support multiple frame input (i.e. size of nframes x natoms x 3 and nframes x 9, respectively). So I tried to do something like this:

// mostly copied from the example
#include "deepmd/DeepPot.h"
#include <vector>
#include <iostream>

int main(){
  deepmd::DeepPot dp("forcefield.pb");
  // 2 identical frames
  std::vector<float> coord = {1., 0., 0., 0., 0., 1.5, 1. ,0. ,3., 1., 0., 0., 0., 0., 1.5, 1. ,0. ,3.};
  std::vector<float> cell= {10., 0., 0., 0., 10., 0., 0., 0., 10., 10., 0., 0., 0., 10., 0., 0., 0., 10.};
  std::vector<int> atype = {1, 0, 1};
  double e;
  std::vector<float> f, v;
  dp.compute (e, f, v, coord, atype, cell);
  std::cout << f[0] << std::endl;
  return 0;
} 

and then compile with:
g++ filename.cpp -L/path/to/dpmd/lib -I/path/to/dpmd/include -ldeepmd_cc_low -lstdc++ -ltensorflow_cc
It compiles, but crash at runtime with terminate called after throwing an instance of 'std::length_error' what(): vector::_M_range_insert (if there're more frames it directly segfaults).
If I also replicate atype (i.e. std::vector<int> atype = {1, 0, 1, 1, 0, 1};) it runs, but the force is NaN.
I also tried nested vectors (e.g. std::vector<std::vector<float>> coord(2, {1., 0., 0., 0., 0., 1.5, 1. ,0. ,3.}); etc.) but it doesn't compile due to no matching function for call to ... (it seems that VALUETYPE must be float and cannot be another std::vector).

So I'm wondering how to use the C++ interface correctly with multiple frame input, or this is not implemented at all?
I'm using version 2.1.5-cuda11.6_gpu installed by the offline package. The python interface seems to be fine (just pass in a e.g. nframes x natoms x 3 numpy array and it works), and the C++ interface is fine with single-frame input.

[njzjz]

Yes, only one frame is supported. The documentation is wrong.

[cihe13375]

documentation is still unfixed :(

[njzjz]

Contribution is welcome.

[njzjz]

It's now supported by #2305.