Quaternion.h

#ifndef QNANO_NEW_QUATERNION_DEFINED_H
#define QNANO_NEW_QUATERNION_DEFINED_H

#include <cmath>
#include <vector>
#include <iostream>
#include <cstdlib>
#include <tools/Vec3d.h>

class Quaternion{
private:
  double u[4];
public:
  double& operator[] (size_t i) {return u[i];}
  const double& operator[] (size_t i) const {return u[i];}

  Vec3d rotate(const Vec3d &v)const;

  void set(double ur=1,double ux=0,double uy=0,double uz=0){
    u[0]=ur; u[1]=ux; u[2]=uy; u[3]=uz;
  }
  inline double norm2()const{
    return (u[0]*u[0]+u[1]*u[1]+u[2]*u[2]+u[3]*u[3]);
  }
  double norm()const{
    return sqrt(norm2());
  }
  std::vector<std::vector<double> > RotMat() const;


  Quaternion(double ur=1,double ux=0,double uy=0,double uz=0){
    u[0]=ur; u[1]=ux; u[2]=uy; u[3]=uz;
  }
  Quaternion(const std::vector<double> &dvec){
    if(dvec.size()<4){ 
      std::cerr<<"Contructing Quaternion from double vector: vector needs to have 4 elements!"<<std::endl;
      exit(1);
    }
    u[0]=dvec[0];
    u[1]=dvec[1];
    u[2]=dvec[2];
    u[3]=dvec[3];
  }
  friend Quaternion operator*(const Quaternion &q1, const Quaternion &q2);
  friend Quaternion conj(const Quaternion &q);
};

Quaternion operator*(const Quaternion &q1, const Quaternion &q2);
Quaternion conj(const Quaternion &q);


#endif