QuadExpr.h

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// Christopher Backhouse - bckhouse@fnal.gov

#ifndef QUADEXPR_H
#define QUADEXPR_H

#include <iosfwd>

class QuadExpr {
public:
  QuadExpr(double v) : a(0), b(0), c(v) {}
  // Named constructor for independent variable
  static QuadExpr X();

  double Quadratic() const { return a; }
  double Linear() const { return b; }
  double Constant() const { return c; }

  double Eval(double x) const;

  QuadExpr& operator+=(const QuadExpr& e);
  QuadExpr& operator-=(const QuadExpr& e);
  QuadExpr& operator*=(const QuadExpr& e);

  QuadExpr operator+(const QuadExpr& e) const;
  QuadExpr operator-(const QuadExpr& e) const;
  QuadExpr operator*(const QuadExpr& e) const;

  QuadExpr operator+(double v) const { return (*this) + QuadExpr(v); }
  QuadExpr operator-(double v) const { return (*this) - QuadExpr(v); }
  QuadExpr operator*(double v) const { return (*this) * QuadExpr(v); }

protected:
  double a, b, c; // a*x^2 + b*x + c
};

inline QuadExpr operator+(double v, const QuadExpr& e)
{
  return e + v;
}
inline QuadExpr operator-(double v, const QuadExpr& e)
{
  return QuadExpr(v) - e;
}
inline QuadExpr operator*(double v, const QuadExpr& e)
{
  return e * v;
}

std::ostream& operator<<(std::ostream&, const QuadExpr&);

#endif