Using h5cpp to write a vector of vector


Hello All,
I know that a vector can be easily written into hdf5 file using h5cpp command:
h5::write( “arma.h5”, “one shot create write”, V);

But I am not able to write a vector of vector in the same manner into an hdf5 file. For example:
const int m = 3, n = 4;
std::vector<std::vector> mat(m, std::vector(n, 1));
h5::write( “matrix.h5”, “matrix”, mat);
would yield erroneous hdf5 write. Can someone help me with the correct syntax here?
Many thanks in advance.