1public: 2  inline curve_rep () {} 3  inline virtual ~curve_rep () {} 4 5  inline virtual int nr_components () { return 1; } 6  // the number of components of the curve is useful for getting 7  // nice parameterizations when concatenating curves 8 9  virtual point evaluate (double t)= 0;10  // gives a point on the curve for its intrinsic parameterization11  // curves are parameterized from 0.0 to 1.01213  array<point> rectify (double eps);14  // returns a rectification of the curve, which, modulo reparameterization15  // has a uniform distance of at most 'eps' to the original curve1617  virtual void rectify_cumul (array<point>& a, double eps)= 0;18  // add rectification of the curve  (except for the starting point)19  // to an existing polysegment2021  /*22  NOTE: more routines should be added later so that one23  can reliably compute the intersections between curves24  One might for instance take the following:25  */26  virtual double bound (double t, double eps)= 0;27  // return delta such that |t' - t| < delta => |c(t') - c(t)| < eps.2829  virtual point grad (double t, bool& error)=...