#include <iostream>
#include <vector>
#include <cmath>

using namespace std;

class WaveFunction{
public:
  double energy;
  vector<double> density; 
};

int main()
{  
  vector<WaveFunction> basis; // a vector of WaveFunctions
  WaveFunction wf; 
  for (int i=0;i<10;++i){ // make a 10 wavefunction basis    
    wf.energy = i*i;
    for (int j=0;j<5;++j) wf.density.push_back(sqrt(j)*i);
    basis.push_back(wf);
    wf.density.resize(0);// REMEMBER THIS; without reset wf.density keeps growing
  }  

  // output just for testing
  for (int i=0;i<10;++i) 
    cout<<"energies = "<<basis.at(i).energy<<endl;
  for (int i=0;i<10;++i) {
    cout<<"densities:\n";
    for (int j=0;j<5;++j)  cout<<basis.at(i).density.at(j)<<" ";
    cout<<endl;
  }
  return 0;
}