double

quadratic (double x, void *params)

{

  struct quadratic_params *p 

    = (struct quadratic_params *) params;

  double a = p->a;

  double b = p->b;

  double c = p->c;

  return (a * x + b) * x + c;

}

double

quadratic_deriv (double x, void *params)

{

  struct quadratic_params *p 

    = (struct quadratic_params *) params;

  double a = p->a;

  double b = p->b;

  return 2.0 * a * x + b;

}

void

quadratic_fdf (double x, void *params, 

               double *y, double *dy)

{

  struct quadratic_params *p 

    = (struct quadratic_params *) params;

  double a = p->a;

  double b = p->b;

  double c = p->c;

  *y = (a * x + b) * x + c;

  *dy = 2.0 * a * x + b;

}